Armour Breaker skill (Warrior) - Do you think it's good?

I was expecting that armour breaking on bosses would be almost mandatory, but somehow I feel like the armour regenerates so quickly again to normal that I only get like 2 of my main attacks in before that.

It feels like I do more damage overall if I just continously use my main attack, and don't waste so much time trying to break the armour before that.

Am I doing something wrong, or what are you impressions / tips?