>>96091983
No, not on top of level. When the bump happens depends on if it's the strong or weak save but 6-7 tends to be the range when a bump occurs
I do highly recommend gradual ability score boosts to iron out the math. One of the few variant rules I think should have been default

If you wanted to give casters access to item skill boosts and high proficiency, then you'd have to change save spells to do nothing on successful saves and give martials easy access to self-status bonuses.
My recommend if you don't want to fiddle around with math to make blasters even better is to simply make spell attacks do half damage on a failure since spell casting proficiency is balanced around save DCs and counteracting