Angstrom

Yeah, I suppose that's fair. You could try a mix of both, maybe establishing a very loose backstory or something just to have a kind of "anchor" for a character and then mostly paying little or no mind to a consistent canon for other things like titty size, setting, time period, etc.

There's always the folks that will pick apart stuff for not being set-in-stone and comprehensive, but I think it's a good idea to disregard them for the most part. Beyond a character's personality and the deeper things that really make them that character, I don't think it's very conducive to enjoyable short-form writing to keep everything else rigid and consistent and pristinely understandable. It's super stifling and suffocating creatively to have to think "Well, I want to draw/write them with x but y is canon, so I can't." or trying to think of how you should connect one thing to the next if you don't really want to.

Maybe it's a bad example, but that sort of thing is how I write stuff with my own character; She has a simple backstory to provide a solid characterization, but I don't really worry all that much about keeping everything else super consistent. Maybe she's in a medieval fantasy setting one time and a cyberpunk setting another time. Maybe she's got hyper tits one time and small ones another. Same character, everything about her that makes her the OC I love is there, but everything else is loose enough to allow for a lot of freedom with writing, and in my experience it's allowed me to really enjoy just about everything I do with her.

Sorry to ramble on for so long, I hope maybe this was of at least a little help, and apologies if it wasn't really useful.