Some varieties of shrubbery can be machine sheared with a hedge trimmer and not suffer ill effects, but many of the varieties we have in Clark County, like this Azalia, should be hand pruned.
Certainly not all, but many of the hedges in Vancouver are Arborvitae, Laurel, Photinia, Boxwood, or Privet. Hedges can be sheared
almost any time of year.
I recommend pruning ornamental trees to fit the space they have, for light and air; so they look attractive, or to produce larger and more fruit.