Genie+ is flawed in that it is still giving out all capacity as quickly as people will take it. That is why the thing breaks down.
The whole advantage of removing the scheduled portion of FP+ was to enable an adhoc experience where guests could be steered based on what is happening 'now'. It removed the burdens of advanced plans and their constraints while making it so everyone (not just those who book the furthest in advance) would have opportunity at passes.
If you don't ensure there is adhoc opportunities - you basically just stripped the system down and took away what some liked about FP+ without giving them anything in return.
I would like to see them simply not give out Genie+ reservations for anything more than 2hrs away. That way you can setup a place where people use standby first, except for things you're willing to invest in, and you commit to that reservation when it comes free. By limiting how much you give out in advance, you undo this 'must stay all day' thing, you give people lots more opportunities, and most importantly you drive an adhoc experience.