I’m playing a wolves beastmaster build and their howl is on a 10 sec cooldown. I put 8 points in Aspect of the Lynx so it lasts 8 sec, resulting in 2 sec where the buff is not up. I then put 2 points into Primal Aspects so it lasts 9,6 sec.
Then I started using a Lucid huge idol that increases minion recovery speed by 11%, so the cooldown on Howl should be 9 sec so Aspect of the Lynx is always up (duration 9,6 sec).
However, it is not always up and the wolves’ Howl still has a 10 sec cooldown.
Btw, the idol in question is called Lucid Huge Nomad Idol of War
The minion increased cooldown effect affects the minions’ cooldowns, not your cooldowns of minion skills. So if your minions had a skill with a cooldown that they used every X seconds, that skill would have a shorter cooldown. The most obvious ones I can think of are the Necro Skellie Rogues with Teleport (8s cooldown) & Shurikens (4s cooldown), Howl is a player skill (which the Wolves can also proc with the Victory Howl & Battlecry nodes).
Anything with “minion” in it affects the minion (like % increased minion physical damage) not the player.