Without chiming in on the speed of unlocking stuff with vanilla WaniKani, I do know that there are a couple threads here in the forums that have basically worked the math out on how to min-max WaniKani and get to level 60 as quickly as possible. If I remember correctly, there are some scripts that you can download that will facilitate this (reordering scripts, I believe, but don’t quote me on that).
I’ve not read through it entirely cause I’ve got no interest in going faster, but there may be something useful there for you