I too find this annoying. The Baths, I think is one exception - you really need 2 hours there at least. But all the other sites, 90 minutes is reasonable and you can then move.

It is unfortunate there is no enforcement of the rules at all. And more unfortunate that more people don't have respect for others. We always try to stick to 90 minutes or less.. only exceptions we make are if there's free balls.. if there are, then we don't rush to leave.