Certified GKH Gardening Expert
It really depends on the type of shrub, but a pruning in spring for non flowering shrubs is normally ok. Most shrubs will not tolerate being cut back by more than 1/3. There are only very specific shrubs that respond to rejuvenation pruning like you are talking about. If you let me know what kind of shrubs they are, I can tell you if you can do rejuvenation pruning on them.