We often compare forms and media in terms of the senses they engage and those they neglect: many writers hold a dream (secret or public) of working in film primarily because it's an audiovisual medium. Sometimes this leads to the (almost certainly untrue) belief that a story would be more powerful if only it were capable of using music and color. Video games also raise the question of interactivity.
I think there are more relevant concerns when we make these comparisons. For instance, while most popular comic book creators seem to perceive their work as essentially filmic, with the major publishers increasingly using art that closely resembles cinematic storyboards and the process of developing a franchise from comic page to theater more streamlined than ever, I've always seen comics as being much closer to prose and poetry, in that they are all fundamentally implicit forms. People believe that they see everything in comics until someone directs their attention to the gutters between panels; suddenly we realize that the vast majority of action in comics is usually happening outside the page, in our imaginations. Not only do we close the gaps between panels (Scott McCloud's closure) but we infer a world outside their borders, and worlds inside the characters. We also, crucially, control the pace at which we read. This gives us time to imagine. Film is explicit. We are, as I've discussed here previously, given insufficient time and space to imagine very far beyond the screen.
I think video games are actually closer to comics and prose than film for the same reason, though (because they don't imagine we have the brains to enjoy anything that isn't basically a movie) game devs would tend to disagree. Games generally unfold at the pace we play them: just as a book doesn't happen unless I'm reading, a game doesn't usually keep happening if I'm looking away (if nothing else, I can pause it).
Another axis on which we rarely compare different media and forms is the ease and commonality of revision within that form. One of the reasons fiction is often expected to maintain far greater depth, clarity, and consistency within itself is the incredible ease and cheapness of revision. In the course of the two years during which I researched, composed, and refined my MFA thesis, I undertook three or four major revisions to the first section of the book, about 20,000 words if memory serves. I rewrote the chapters, rearranged them, cycled them in and out of various persons and tenses, refined them, extended them, combined them, divided them, recombined them, cycled their tenses and perspectives further, altered the character of the narration, changed the events, changed the events again, and changed the events again, not in that order, in a recursive process that continued from the novel's first composition to its last revision. Even the most extensive revisions never took me more than a couple weeks, and they never cost me more than the hours I spent on each section. It wasn't many hours, either: you can write a novel in your spare time, time you might otherwise spend on television or Internet surfing, and you can usually revise it in a much smaller quantity of the same.
Words, meanwhile, are practically free. If you can afford electricity and a small laptop (the machine on which I composed my novel cost me $500) then you can afford to write as many words as you like. The keystrokes are effortless. For some of us, composing a good sentence can take quite a while, but most writers generally achieve a fluency of style that allows them to work fairly quickly: so long as they can find the proper content, putting it down on the page is little trouble. We take all this for granted, but not every medium shares these properties.
On this axis, film has weird proximity and distance to writing. A good screenplay is generally under development for years or decades, though it may not contain that many actual words. If you're a screenwriter in it for the art, there's little reason not to revise, rewrite, revise, and revise again: your product is in no demand, your supplies are cheap, you have time. When the time comes to produce the film, further revisions will doubtless take place, now under new constraints: the director, the producers, the studio will all have their own needs and suggestions, and these may need to happen very quickly according to a schedule that's out of your control, and they may be forced by the absence of money (we can't afford to shoot that!) or the presence thereof (we've got ten million for effects in this scene, let's go crazy). As the footage takes shape, further revision becomes necessary, and in big-budget films this revision may be possible entirely within the computer, or there may need to be re-shoots, or the editing room may be enough. In a lower-budget film, meanwhile, these things are expensive or impossible. Even time in the editing room may be at a premium. There is pressure from the cast and crew to create a product. In film, revision is often necessary and sometimes affordable, but you never know when the changes you most wish to make will be possible and when they'll be out of reach.
A musician might never stop revising, but the record might not reflect these labors. Every performance is an opportunity to transform the material, but the CD's won't rewrite themselves. There are many bands known for being better live. Their records can't keep up with them. Studio time can be expensive. The more successful you are, the tighter your schedule. If no one knows you exist, you can record for as long as you want.
The least frequently revised forms are television and comics. Both are usually serial forms. Both rely on "retcons," or retroactive deletions and corrections, more than any other forms. Comics writers rarely revise (as far as I can tell) because they don't have time, and because they don't care to try; they have to deliver the script on time to their artists, and they can't show it to anyone else for feedback if they're going to do that, and furthermore for the most part no one really cares if your comic's writing is sloppy. Writers might benefit from scripting entire books at a time rather than chapters, but the incentives never line up for this sort of planning ahead: it's nearly impossible to form a writing/drawing partnership, so if you have an artist you are writing for that artist NOW, and if you don't you can't commit to a script anyway. Artists expect input. If you're part of a team writing for Marvel or DC, that's a little different, but it only makes revision less likely: now you really don't have the time. The monthly schedule favored by the major houses is punishing and leaves little margin for error.
Comics artists, meanwhile, are in a still rougher position, because their work is so laborious and time-consuming, and because it is not usually very profitable. A great comics artist can probably make more money on a given project, at the low end, than a great comics writer, but he does so at great cost to his time and sanity. Drawing is hard. Drawing well is extremely time-consuming. It also requires intense initial investments, whether in finite resources (ink, paint, etc.) or expensive technology (computers, Adobe graphics software, and so on). While the processes of thumb-nailing and sketching common to many comic artists provide opportunities for marginal revision, the major details are unlikely to change. A few auteurs (Chris Ware is known as a particularly devoted revisionist) will break with the trends, but generally once a comic is drawn it stays that way forever. Changing it is simply too difficult, too expensive, and too time-consuming. Marvel and DC artists are in still worse shape: most of them genuinely can't keep pace with their schedules, and as such they especially don't have time for refining work already completed, even if the work is subpar.
The process in television can change from series to series and season to season, but the key differences between television and film are time and money. Episodic television must be created on exceedingly tight schedules, and while some baseline level of collaborative revision will take place with any script, I don't think you'll find a lot of TV writers complaining about an excess of time. There is less room for speculation in television, meanwhile, than in film: a TV show is, for many reasons, generally a more thoroughly quantified entity than a film, with likely floors and ceilings on its achievements. You don't spend ten million on a series hoping to turn it into a hundred million. You spend what you've got and hope to make more or less what's expected. Even a putative hit may not ultimately be that lucrative. So ultimately, you make the show you can make, the show you have time for, the one you can afford, and then you move onto the next. If a season of television doesn't quite add up, you can't go back and fix an earlier episode to make the whole thing work better: even if the studio would allow it, your audience already saw the original version. Things are tight.
The good news is that your audience understands your challenges. People accept failures and excesses of storytelling in television and comics that they wouldn't put up with anywhere else, mainly because they know on some level what the creators are working against. But their patience does have its limits.
I am painfully aware that this has all been very general. I'm planning to explore some specific examples of processes of revision (or revision's noteworthy absence) in various forms and contexts in coming days, starting with a post on Friday Night Lights. If you'd like to talk about your own approach to revision in any medium, please do.