I’m playing Champion only so I’m referring to this difficulty.
Since patch 1.2.1 beta it seems to me the number of specials (and hordes btw) is increased.
Before you met 4 specials at time. Now it seems you are getting more than this number and more frequently.
Played FG and we couldn’t make some steps without 4 specials appearing.
Just ended a CoD mission and in the last part, at the 3rd tome’s, at least 5 specials appeared back2back.