Yes, I did mean time rather than space in referring to P23/24.
As for the housing, I think they really wanted to maximize the number of beds they could do, and that meant they had to do it on Block 15. So I'm okay with the tradeoff...Block 23 would have been nice with the Gene Friend Way plaza and the light rail stop, but it's still pretty close to that area.
The tall parking garage is also a tradeoff. Block 18 was originally supposed to be entirely garage...actually two separate garages totaling 1800-1900 spaces with 6th Street running between them, but they've been able to eliminate that block of 6th Street entirely from the plan. But with community concerns about UCSF turning its back on Owens, they've decided to put an office tower fronting along there with the garage behind.
So by going vertical with the garage and eliminating 6th Street, they're able to squeeze in 1544 spaces (plus 60 shuttle spaces) while also getting the office tower on one side and a larger sports field on the other. We fought long and hard for a sports field...it almost went away entirely or put on a rooftop. Unfortunately there was also supposed to be a couple of tennis courts or similar smaller-scale recreation on Block 15, but that has to go for the housing.
So yes, a tall parking garage isn't ideal, but I think it's a good compromise given what can be achieved with it. It's also important to note how successful UCSF has been with the shuttle system and on-campus housing. The original projections were for 4600 spaces for the campus, but it looks like they're going to get away with only around 3000. There was originally supposed to be a 1000-space garage on Block 20, but that disappeared from the plans with the first housing project. They also seem to not be including the potential 375-space expansion to the Block 23B garage in the latest plans.