Answer: While most hollies will take some pruning and even tolerate shearing well, drastic defoliation is a serious problem because it takes so much of the plant's energy to sprout the replacement leaves. As you have noticed, different varieties of holly may respond differently, and younger wood will regenerate faster than older growth can. Well established plants will recover faster from stress than newly planted shrubs. Eventually they should fill in to be symmetrical again as long as the branches are sprouting new growth.
If there is any dead wood on the plants, remove it any time. If there are occasional stray branch tips reaching way out of line, nip them off also. A light shearing can also be done. You will notice over time that the branches become bushier where you have cut, so keep this in mind as you decide where to make your cuts. However, since the setback was so severe I am tempted to suggest leaving any extra growth to supply energy to the plant to add in regaining vigor and then trim it back as hard as necessary early next spring.
To help your hollies stay as healthy as possible, be sure they receive adequate water throughout the growing season, consider using an antidessicant spray this winter, and consider applying compost annually. Consider a soil test to be sure the pH is acidic enough.
Finally, if at all possible protect them from the marauding deer. You will probably need either a fence or some sort of cage around the hollies. Some gardeners report success with repellent sprays and with assorted home remedies, but if the browse pressure is severe as it appears to be, the only truly reliable protection in my experience is a physical barrier.
Good luck with your shrubs!
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