I don't plan my UI .. it's more like an evolution :)
But that's what happend when I used trinity bar in the beta with my warlock ... I made a bar for summoning my deamons... later I respecced to demonogy and got felguard.. I added a few buttons to a bar for felguard and soullink and what I got.. I noticed I made a button to much ... told it to remove one.. it removed one on the wrong side .. I pressed add to get it back and got a new button again on the other side... in the end I removed all actions from all buttons and started from scratch.