So my warlock just hit the magical level where imps start literally throwing themselves out of the twisting nether to help you with fireball goodness. Which is nice. I really appreciate their efforts and all, but I think they may be working a little too hard.
See, the tooltip says the effect can occur every 19 or so seconds; in execution however I've noticed that the delay in getting the buff back varies from no time at all (I've had two imp procs in a row from back-to-back Shadow Bolts) to 15 seconds, but rarely does it take anywhere close to 19. My latency was pretty low at the time of testing so I don't think this was a lag issue--in fact if it were it would take longer for the buff to come back.
I mean, if it's working as intended and I'm supposed to have an enormous raid group of imps following me around blasting my enemies to bits, then rock on. But I always feel bad taking advantage of an ability that seems to be more powerful than the tooltip indicates.