"For example, having crafted 250 of an item would give you 25% extra productivity on that recipe (10, 20, 40, 80, 160) and your next bump would happen at 320 crafted."
But....10+20+40+80+160 = 310., not 250.
...or, wait, do you mean you reach the 25% productivity once 160 is crafted, thus the next bump (+30%) is gained at 320 items total crafted?
