Heavy summer pruning and shearing during the summer can be tricky. If you can, wait for a few cloudy days or limit the pruning to plants that are in the shade or out of the sun in the afternoon. And make sure not to schedule a major pruning like I did before a heat wave. This pieris did not appreciate being snipped before four days of 90 plus weather and got a nasty case of sunburn. Oops.
What to do after the damage is already done? Go ahead and prune to shape. You'll get a new flush of growth before you know it provided the plant or tree is healthy. Once the weather cools down for good this fall spend some time snipping out those old burnt leaves so you don't have to look at them anymore or just let time take it's course and let them fall naturally. And next time, wait for a cool cloudy week.