Likely diminishing returns. It also means you're likely crit/det starved.

The good news is, since we get to the sweet spot of skillspeed so easily now at i190, i'm sure by the time we hit the 3.0 ilvl gear cap of like 230 or whatever, we won't need more than maybe 2-3 pieces with skillspeed on them. Then we can load up on det/crit once we're acc capped.