Monk Round Kick
 

Hitting the "Round Kick" hotkey as soon as it refreshes brings up an error.
Something like "ability refresh timer has not yet been met".

This causes the Round Kick to Not occur and the timer to start over.

I mash the Round Kick hotkey in close fights and this just makes things worse.

Same for Monk Eagle Strike. I just chalked it up to the fundamentally crappy mechanics of EQ (not the P99 devs' fault) where the client gets a message that an ability is ready, but when you try to use it, the server says it's still on cooldown.

I haven't experienced it for a while though, but that might just be because I got into a habit of not using it the instant it pops.