My advise to you: Don't repair when it doesn't need repair.
That's definitely the strategy to use given the repair system that exists in this game. But are we really supposed to let things break and repair them afterwards? The way things are this might be the best way to prevent durability loss but that forces us to behave in a way that makes no sense whatsoever and is unduly inconvenient.
I'm really surprised nobody has complained about this before, I've never seen a repair system so cumbersome in an MMO or any other game type and I study games and gaming for a living.
It doesn't take a genius to realize that the repair system is set up this way to force people into buying AP for repair hammers. Having dishonest elements in a game like this is only going to poison the player-company relationship and will drive many players away who are smart enough to figure out what is going on...
I might be the only one to post a thread like this but for every person who says something there are tens, maybe hundreds, who don't.