A very random thought came to my head today, and I had to watch this episode again to check it.
Buffy and Lily enter the hell dimension at different times. Lily falls in first, and Buffy follows (with Ken) roughly 7 seconds later. If my calculations are correct, that would mean that Lily actually waited for Buffy for 70,97 hours, or 2,96 days - but it looks like Lily just recovered from her fall. Unless of course the portal somehow predicts that three people (well, two plus a demon) are going to fall through it. Or that the area immediately below the portal is some kind of lobby for the actual dimension, and the timewarp happens later (unlikely, as we don't see any other portal-y things). Oh well