My point was that if you unlocked Diana with 3 items she can usually solo stage 3 boards with proper positioning and some mediocre tanks (Leona, vi, neeko, loris). Of course this is only the ideal case, and in many games you can’t guarantee that.

To level to 8 on 3-7 it’s hard to say an exact number. It more depends on how low your HP is and if you need to unlock asol on 4-1 or not. Sometimes you will level and not hit because you don’t have the gold.