I largely blame inescapable torment and mind devourer for this, as this point is especially true during our burst windows.
Our insanity generation is low-moderate outside of mind bender and shadow crash and then it spikes virtually uncontrollably when mindbender is popped. This would arguably be a good thing, but the issue is that inescapable torment requires us to cast mind blast + shadow:word death during a time when we’re overflowing with insanity. Mind blast in turn is what procs mind devourer.
Effectively the issue here is that we already have too much insanity while our #1 priority during burst windows is using an ability that generates insanity. Then we get a mind devourer proc which makes our abilities cost no insanity.