At Colgan, we use torque as our power indication. ITT is just something we don't let get over a certain number, depending on what phase of flight we're in.

But, we don't set 850 degrees on both engines and call that cruise power or anything like that.

We don't have PT-6s, but I can't imagine it being any different no matter who made your turbine engine.

I think the misconception comes from the fact that the cruise powers are charted with the intention of keeping ITTs at a desired level, so the manufacturers tell you to set 80% torque, but what they really are concerned about is keeping the ITT below some number. Pilots who know this then try to put the cart before the horse and just set the ITT to that number. While they are not exceeding anything (as long as the other indications stay in the normal range), they are not doing the engine any favors, and are shortening the time before it needs a hot-section or overhaul.