planetary
EndlessCheese spreader
The limit of 4 custom and 2 favorites is because that's all they can fit on vertical format screens. If they give the 3/Y more functionality than S/X, owners might complain. (lol). But also, keeps the software more universal across models.
I think you mean "legacy Model S/X", i.e. those with vertical screens. It's ok to have more features than those cars.