It takes forever in higher tier to get to the next heat level, the higher tier your weapons, the lower the chance, and that's terrible.
Trying to upgrade my weapons but at the same time not even being able too is annoying.
The new heat system is terrible and a waste of time, I liked the old one, where it leveled on its own and it was actually a reward, unlike now, where you only do it if you have the luck + crystals.
Wait till you see when you get to heat 4* and 5* stuff to around level 7, 8,9 and 10. You start needed around 64 crystals to level up with 100%, it's insane. And you cant buy your way out of it: 350 and 700 energy for only 50 crystals? That doesnt even guarantee a level up!
The new heating system is atrocious (specially when you are heating multiple stuff) but it's mostly to balance the fact that elevators are now free :\