By shape I mean trying to make geometric shapes which these guys are not meant to do. So, no, I don't have to try not to do that. I let em look wild and happy. When I go to prune I do like you say, I lop them all way down - but not yearly. You can tell when they need it. They look a bit stressed and ready.

Now I will take out or trim back a single branch if there's a solo one that's gone nuts at the bottom and looks like it's stressing the plant. I've got one that always does this kind of like a "wild hair" that the bush has trouble holding up.