i'd imagine the advancement of time would fall under the "plot" category. The plot needs X amount of time to pass, and thus it does. I'd imagine that time will advance slower within a given thread, due to them being microcosms on the site. (Even a large thread like the Lockerroom is just a small part of the events.) For the site as a whole, I'd imagine it'd be more sporatic, with some sudden leaps.
All-in-all, I play it fast and loose. I prefer threads with fewer people in them (as well as a posting order) since I have a 40 hour workweek, plus transit times, plus errands... so, I prefer a slower pace. Even when I fall behind in a large thread, I usually either play "catchup" with my next post, or silently leave, since my presence by that point is probably a non-issue.