Aside from mops, I wouldn't give any pitcher a max PC of none.
In-game fatigue will catch up to any pitcher. Peavy's highest IP/G is 6.77, which means he'll be "fresh" for just over 100 pitches. If I wanted to "stretch" him, I'd put his max at 120-130, tops.
To disregard a pitcher's IP/G is to play with fire, IMO.