Chicken-and-egg, I suppose. Once I've got all the relevant bits and pieces together to inform my roleplay - including the various choices I've made during char-gen plus the numbers the dice have given me to work with - I'll then come up with the basics of a personality and outlook for the character. Then, once the character comes into play, the in-game decisions it makes (or that I-as-its-player make for it) will ideally be made through the character's eyes and as extensions of that personality and outlook.
To me this is more immersive, in that - again ideally - I can "inhabit" the character right from square one and make decisions as if I was the character.
More immersive than what, though? I think there's a difference between making decisions based on what I think my character would do (which I don't find very immersive at all) and making decisions as my character. Is that the sort of difference you have in mind?
What ends up happening there is you get two characters in one: the character that the sheet seems to suggest, and the character you're actually playing. If-when these get too far apart, as either fellow player or DM I'm likely to raise a squawk.
All I can say is I agree with
@Campbell's statement up-thread (if I'm remembering/paraphrasing correctly) that any perceived discrepancy between my character as established by in-game events and what's written on the character sheet should be settled in favor of the former.
I see it more as in RPGing you don't have to worry about reaching the point of the script and blocking restraints disappearing from your consciousness, because they're already gone to begin with. From there, it's easy enough to just inhabit the character and have it do what it would do.
The character doesn't do anything without the player deciding what it does. I find that my immersion depends on those decisions closely resembling the decisions people make about what they themselves do. I don't think most people's decisions hinge on ideas of what they
would do. I think people are more concerned with doing what they want to do or what they think they
should do. I mean, who makes decisions by thinking about themselves and what type of person they are and then asking themselves what that type of person would do?
Semantics, perhaps, but when I think of "authoring" what comes to mind is preparing something ahead of time; as opposed to improvising where nothing is authored and it just happens. Sure, after the fact one can look back in hindsight and say things were authored, but in the moment I don't see that as what I'm doing (and I'd think it somewhat pretentious if I did).
Improvised authorship is still authorship, but I think I get the distinction you're making. I don't think of myself as an author when I'm roleplaying (unless I happen to be roleplaying an author). I think of myself as the character. What results, however, is an act of authorship. I made something up about my character.
I certainly do, as one of those underlying game-based processes is - within reason - to play to your numbers.
Would you say that, in your games, and seeing that this thread is in the D&D forum, that this is seen as an unstated rule of the game? It certainly isn't in my games, but I think if it were a rule or had some mechanical backing in the rules, I might be more tolerant of it as a resolution process. For instance, if I as a player had to succeed on an Intelligence check for my character to make the "come up with a plan" move, I wouldn't find it nearly as un-immersive as trying to gauge my character's plan making to its Intelligence score.