[2020] Suggestion; Make the simulacrum key from a stack of 50 splinters instead of 300, and each key will add 5 waves. You can then use 1 key to test your build or go 4-5 key to get more loot etc.

I know this isn't the exact suggestion here but I just wanted to take this opportunity to mention that the drop rate for the Simulacrum splinters has been increased for Patch 3.10.d - looks like this is coming out today.

It's in there.

That was fixed earlier this week.