The nature of HT is last minute spur of the moment bookings.
1. Those that are in another city, knew they were going to be there, and didn’t book ahead (or just need an extra room?)
2. Those that live in a city and decide to get a hotel room tonight.
I’m actually having a hard time figuring out who’s booking last minute (and why a site specializes in it) other than for parties (large groups or.... by the hour).