User blog comment:Kitahara/Recording drum expedition success rates/@comment-25730832-20150206083101/@comment-25832576-20150214024557

As you two might be aware, I've been done with the event for several days now. But I continued trying the expeditions with more drums equipped until the second batch of sparkles ran out, and the results are...pretty interesting:



Something to note was I did exp 21 with 2 drums on each ship instead of 3. Sample size is too small to see if it actually made a difference compared to 3 on each ship, but the two failures compared to 3x drums could suggest there isn't a limit to how much drums can help. I don't really care about the specifics right now, main point is this is a +1 for drum stacking.

So now the pieces are starting to fall into place, and I'm starting to feel it goes something like this:

It starts with a base rate of 15~20% with the minimum required drums, plus an extra % for each additional drum, generally up to another 15~20% (this might explain why I notice people finding exp38 gets GS less often than 37)