I find myself thinking a lot about the goals of different writing mediums. When an idea comes to you -- do you always execute it in the best medium? Obviously most writers have their one or two formats: poetry, flash fiction, short fiction, novella, novels, memoir, essay, short or long form article, non-fiction book, documentary, monologues, plays, web-series, half-hour TV, one-hour TV, feature film... to name a few.
For me a lot of these don't come into play. My writing attempts have been, in no particular order: poetry, most lengths of fiction (never completed a novella/novel though), essays, and one-hour TV (some features too). But many times while the idea is clear the best medium is not. This "valence" issue especially pops up for TV vs. feature screenplays -- but the question could apply to almost anything.
With TV, I think it could ultimately be a question of character. Are these characters that will continue to live with their problems and conflicts, or does the character require a concise or definitive arc? Many times a plot can be broken and re-broken a thousand times to fit around the needs of the rest of the story. That's certainly something I'm trying to teach myself to do, since a lot of pilots end up feeling "cinematic" in all ways -- bad too, since it feels like it's just ended, how will this story continue indefinitely?
But it also got me thinking about poetry, a medium I've attempted time and time again (go back all the way to the beginning of these posts for an example) but always feel I've failed at. I think, to justify a poem - the poet needs to examine the most basic building blocks of language itself. The smallest unit of writing needs to be self-aware. It's like physics -- the letters are quarks and the poet needs to be aware of every movement, every application.
Whereas short fiction, well there's a little more breathing room, right? Each sentence needs to count, needs to do a ton of work, but ultimately it's about the story you weave - not the fabric with which its woven. Poets can tell a story too, but it's about so much more than that. If poets are the physicists of writers then short fiction authors are... chemists? Your basic materials are a little larger, while still being under the microscope.
Screenwriters and playwrights and folks of those ilk -- I feel like they're more mechanics (machinists?) than chemists. I'm not really sure how far I can extend this metaphor. Chemists and Physicists can take apart the whole world under their lens, while mechanics know exactly what they can and cannot build, take apart, reconfigure. It's limited but still challenging and rewarding.