We're saying the same thing differently, Ringabell. Each fate has the same drop rate, and that does not change. Each has a an independent outcome that has an X% rate of drop - just like your coin example. It becomes less likely that you will fail at achieving heads the more often you flip the coin. The same goes for each atma drop. It is less likely that you will fail the more you do. But that doesn't change the fact that each drop is independent of the last and does not affect the next or last.

BTW, I fell into the trap of believing that there was only one drop per fate as posted by someone else before. That was dumb.