Defoliation is a balance of science, art, and experience. The thing to remember is bud sites need light, but they also need leaves. Experience tells me where to stop trimming. Sometimes I still go too far or not enough. Trimmed my first plant in 1984. There is no "rite" answer for "how much??" Its specific to strain, and even pheno.
My advice... yes, defiliate when you think you should, as much as you think. If you get it rite cool, if not you learned something.
Don't sweat it man, these things are hard to kill.