The best way to learn is to push your limits and fail. If anything, you aren't failing enough.

The very best players will occasionally eat dirt BECAUSE they are pushing that boundary. They're the ones that will get clipped by AOE pushing for an extra attack, or let the tank die because the heal came 0.1s too late, or not use a cooldown because they think they can take the hit -- and can't. Then they adjust, and ride that line, because they know exactly where it is, and pull off some amazing play.