If they still look good then leave them alone. Like the old saying if it aint broke dont fix it. Just enjoy.

Pinch back every other one now and in a month pinch the rest. Follow with a good soaking and Miracle Grow

Don't cut them all back at once. Start with the really leggy ones and as the plant begins to put out new growth, remove other branches you don't like the appearance of.

I just did the same thing, sort of, here in NYC. Just for a diff't reason... one color was completely crowding out another so it got pruned back.

I find that the most helpful thing to do with them when it's hot is to move them where they get no sunlight at all, make sure they're mulched, and water WELL every night.

Pruning isn't a necessity for these plants. I find that when they get leggy, simply adding Miracle Grow sticks is all they need. Many Impatience varieties also get leggy because that's simply how they naturally grow.

Hope that helps.

I think Southern Living had an article about cutting them back for a Fall big hurrah last year. I do cut mine back if they're spilling so far over the paths/walks that I can't get past them and I also pull seed heads here and there right about now. I also do a little pruning to keep cuttings alive over winter inside in late August to mid September (for planting out next Spring.) Mine typically go into high gear in September and are still pumping out the blooms until Halloween if there hasn't been a frost.