Ok, lets see this examples, ok? :)

33% chance on Heals to remove 1 Negative Effect on the target. This can happen no more than once every 30 seconds.

Critically healing an ally grants them a 3478 damage shield for 8 seconds. This effect has a cool down of 6 seconds.

I always wonder if the cd is on you (on the set) or the target.

If its on you, you can only remove one effect every 30s or put a 3k shield every 6s.

Id its on the target, you can only dispel or shield a player every 30s/6s, BUT you can dispel/shield any other player (with its own cd)

...Its the difference between being an awful or interesting set.

BTW, before you tell me 'try it yourself': I'm on pS4, so I don't have any addon to help me discover the truth ;)