SoC bugged, or unlucky?

I have been noticing more and more lately that for at least 50% of my mobs I will go without a single SoC proc, which means it takes me so long to kill something that I have to re-cast SoC. At 7 ppm, I should be getting 3-4 procs per cast.
This does not seem to be the case, so is SoC bugged or am I just unlucky?
I am using a 3.2 speed weapon, would a slower weapon make a big difference?
This does not seem to be the case, so is SoC bugged or am I just unlucky?
I am using a 3.2 speed weapon, would a slower weapon make a big difference?