It is really helpful! I’ve used ideas from my one-page-stories for longer projects many times, or even just to help think of specific plot points or certain important moments within stories.
I do add choices, sometimes. I really just sit down with an idea and run with it for however long until I want to turn to my main project instead or, if I’m doing it as a stress-reliever, when I’ve relaxed some and feel ready to turn back to whatever it was that was stressing me out.
Some of them really never get past the first, introductory, page, which is where the exercise earned its name from. Other ones have gone on until I have maybe half or even more of the prologue done. I don’t think any have ever really gone past the prologue, save for one or two with exceptionally short prologues… but even then they only ever bleed a little into the first chapter before I feel ready to move on. Since the length varies, whether or not I add choices in varies as well.
As for stats… well, some of these are created for the sake of just messing around with specific kinds of stats, in which case, yeah those do have stats. Other than those ones, however… most really don’t have anything to them. Maybe one or two stats, or the usual ‘name, gender, pronouns’ stats in case the MC is referred to at any time within the first few pages but… others not so much. I don’t really stress about stats until after, if they become a larger story.
With these, I’m not really going in with the expectation of writing anything to keep (or, heck, even trying to write something good). Just having fun with a story idea or two and maybe they jump out at me and I want to continue with the idea, or maybe they just stay as a little practice.