Please reduce the CD and duration of Arm's Length.

[KDSilver]

When can you actually use that ability for preventing drawback? Every time I tried it to cover for mechanics, it ended up not working.

You're using it too late then. If it's on a cast bar, you have to use it before the cast is over, not relying on the animation.
As for knowing when... well that's the point. Playing the game and the content and what pushes you, and when to use it.