A cooldown on being exhuasted

I was thinking how sums like heal have a cooldown how often you get healed with reduced effects offensive ones should as well example if you get exhausted twice with in 10 seconds the second one should only be half as effective same with ignites it rarely happens but it makes the game a real pain sometimes when teams have more then 1 exhaust on a team the only counter play to being exhausted multi times is hoping your not the only threat on the team and they exhaust someone else .