The trouble is a lot of bids on RBs are from the deluded/unappealing/crazy/dusty phone end of the market...I even had a tranny bid on my last one and I specifically asked for a female. Attractive girls that offer good service are busy enough without having to bid on RBs, though you can sometimes turn up a gem for a sensible price.
Never tried reverse booking for this reason. The best restaurant on the high street does not offer 2for1 deals; good hookers are busy enough without having to proactively seek out punters.
To the OP's broader point, most WG's will say they start at 11 but few are reliable at this time. My guess is 2.30pm will find more girls with time available, particularly if you make a provisional arrangement the day before.
It seems to me that most popular girls make up their rota on the morning of the day they work, If they have seen you before, and you impress as reliable, they may be keen to get you to fill less popular times. Most seem to be about trying to form a regular rhythm of booking that maximise earnings and minimise problems (overlapping bookings) across the shift. I am pretty sure most girls do NOT book back to back if they can avoid it - but the pimp will try to manage 100% room occupancy and this contributes to you being hurried out at the end of the punt.
If you are looking for value and choice I suggest
1) Tuesday through Friday
2) Mid afternoon
3) Call a day in advance and make more than one tentative arrangement unless the WG in question has a good reputation for reliability
4) Agree when and how you will both give final confirmation for the morning of you booking
It
isn't very spontaneous, but it reduces your chance of a no-show.