thomis:

I prune stone fruit mostly after harvest. But do prune at other times if needed to open up the tree. In fact that's usually my first step in thinning fruit.

Same here - I try to prune after harvest but if I find a too-dense spot its being dealt with right now. In general I believe it is good to view pruning as a continual operation, keep chipping away at it. I made a couple dozen pruning cuts in my thinning pass through my peaches and plums this morning. By the way I also spread out the thinning, its done over a period of several weeks bit by bit. It allows inspection of trees for other issues while thinning. The fact that I don't thin the cherries puts them at a disadvantage, they are not getting as much attention.

Scott

I've recently become concerned about my old methods of summer pruning peaches. Turns out leaves on this years wood send sugar down stream to fruit quite a ways. I've usually been pretty ruthless in opening up the trees all season long and I think I may have reduced sugar of fruit. It's a bit of a balancing act but I think the trick is not to prune in the mid part of main growth. Prune early and prune some when the trees are about a month from ripe.

Up here, main structural peach pruning is recommended not after harvest but around bloom or a bit before. This reduces the chance of canker because wounds close most quickly at this time. I guess if you still have some good season left after harvest there'd be some real benefit in getting light down to next years fruit bearing wood. Maybe that's why Fruitnut finds it useful to prune at that time.

Here it might increase risk of winter injury.