Pruning trees when dormant vs growing?

I've always pruned in late winter with the idea that it reduced chances for disease.  This year I started doing some pruning in the growing season because it let me head off undesirable growth before the tree pumped a lot of energy into it, and also gave me fodder for the livestock.  I really prefer the growing season pruning.  What do you do?  Will I regret it down the road?

not sure if it depend what kind of trees.
I learned from somewhere that peach trees should be pruned only in spring when they are flowering. and high bush blueberries all that's necessary is to clip off dead sticks and branches. but that's just my experience.

When to prune depends very much on the plant and on what you want to achieve.  In general, it's better for the plants themselves if you prune them in late winter/early spring, when it's started to warm up but the plants have not started to leaf out their spring growth. It's less stressful to them, their wounds heal faster and it directs growth to where you want it.  Prune in the summer if you want to retard the growth of the plant and make it smaller. However, you should stop pruning woody plants 6 to 8 weeks before you expect frost in order to allow the plant to heal and harden off properly before winter comes.
Another consideration is if and when the plant blooms and whether it blooms on old or new wood.  For example, rhododendrons bloom on old wood and set their buds in the fall for spring blooms.  Therefore, you'd probably want to avoid pruning them in the late winter/early spring because you want to keep the buds.  A good general rule is to prune blooming plants right after they bloom.
And yet another consideration is what pests you have in the area that may be invigorated by your pruning. Where I live, we avoid pruning pines at certain times of the year in order not to attract pine bark beetles.
Those are all general rules. I keep a chart of what plants I have and when I should prune them. Different plants have different requirements and my chart helps me not forget what and when I need to prune, so I am not forced into either pruning when I shouldn't or neglecting to prune a plant that year.

I've both heard and read about some genuine benefits of summer pruning. I wasn't as aware of this outside my ecosystem which is very rainy in the winter, thus a rather miserable time to be out pruning.

A friend talked me into buying an espalier pear tree for a spot that I didn't want a tree that would cast shade. The instructions specifically said to prune it in August and generally it has done well under that protocol. The issue is that despite my efforts, the deer keep breaking in and eating all the leaves. I have had to try and let the tree grow a little taller to keep some of the leaves out of reach.

I recently read Grow a Little Fruit Tree by Ann Ralph which advises summer solstice pruning to keep tree size in check (but not too close to fall as this type of pruning promotes growth, same as winter pruning). I did this (the solstice prune) for the last 2 summers and it worked well for the cherries that got too tall. I still winter prune for all the usual reasons. I tend to underprune anyway.

I do both now. Winter pruning for the structural stuff, removing crossing branches, shaping the canopy. Summer pruning to keep vigour in check on anything that's getting too tall or pushing growth where I don't want it. The summer cuts heal faster in my experience because the tree is actively growing, and you can see exactly what you're working with when everything is leafed out. Only thing I'd avoid is pruning stone fruit in winter because of the canker risk, those always get done in summer for me.