Tangs IMO, are 24/7 grazzers. It doesn't matter that you feed them 3 times a day, if they happen to be hungry between your feedings.... like any animal they will turn to the next available food source... your coral. that's nature.
Well I don't have a Pt but want one in the future. After reading this though I will have to reconsider it. I have 3 large tangs now and don't have any issues with them nipping at my LPS. I do have a large Majestic that is starting to have a taste for corals. It will be trapped and need to find it a good home soon. I hope my 3 tangs don't start to have a taste for corals anytime soon!
Good luck with this, in my 300 gallon tank I had 2 PT and 4 yellow tangs. The dominate PT mowed over every zoa colony I had. When I setup the new 200 g. cube, the PT and 2 yellows went up for sale. I can finally keep zoas again.
My PT has never nipped my corals at all. I keep mainly Zoas. Sadly I'm seriously thinking of downgrading to a Nano. What I'll miss most about having a larger tank is my PT and the option for other beautiful tangs, wrasses, etc.