Let's talk about discharge recovery

What does it do: Decrease your cooldown on an impulse charge.

What I don't know is if there is a cap on it and how exactly it works. Let's say I have 20% discharge recovery. Would that mean I can get an impulse charge every 8 seconds instead of 10?

The reason I am asking is, that spirit seems to scale a lot better then luck when just looking at the 'added damage' value. So I am wondering how far I can push the proc rates on impulse as it is more controlled dps then random crits.