I think key depletion should have breakpoints on levels where they add affixes.
- +2 → +1
(timer + affix) - +3 → +2
- +4 → +3 (new affix)
- +5 → +4
- +6 → +5
- +7 → +6 (challenger’s peril)
- +8 → +7
- +9 → +8
- +10 → +9 (both tyr + fort)
- +11 → +10
- +12 → +11 (affix replace)
- +13 → +12
- +14 → +13 etc
Reason being that these breakpoints that add a complexity that can’t be practiced on lower levels. This way you still expecto depleto trying to push up for your current difficulty, but no longer try to get keys back up on a difficulty that you can easily +2 compared to the key you’re trying to do. This is especially annoying to do on a +11 vs +12.