I think all sprint FP sessions should be 90 minutes
After the extended practice in Miami, it occurred to me that there was no reason we couldn't do that all the time. I know it was intended to be a one-time thing due to extenuating circumstances, but I don't see why it couldn't be permanent.
I know teams hate the lack of prep time, and while this wouldn't be a full replacement for the two hours lost, it would at least give a bit more breathing room for running all the tests they need to, and only 30 minutes shouldn't really disrupt the rest of the race weekend with all the support races. (You could maybe even be a bit more liberal with allowing recovered cars to be fixed and sent back on track if they failed for non-crashing reasons, like in testing.)
That extra time might just make the teams a little bit more secure in their setups and make for slightly better/fairer racing. It seems silly as an organization for F1 to kneecap their competitors' ability to put on the best show possible, and if they're not gonna scrap the sprint format, might as well revise it and try to make it the best it can be, no?