I’ve always been amazed at the plant’s ability to produce new leaves. Almost anytime I look at one of mine, I can find a few fan leaves to come off. They never seem to mind.
I liken defoliation to trimming one’s hair or nails, nothing major. Once I go into flower, I trim all growth from the bottom 1/3-1/2 of the plant. Directing the nutrients upward from the roots to flowers is a concept I’ve encountered again and again in my research. It seems reasonable to trim away branches and leaves that will never amount to much.
Recently watched Mr. Growit interview a man named Jorge with over 40 years of growing experience. Jorge seemed against defoliation but I can’t see not doing it at least periodically.
It sounds really corny but I’ve learned to listen to my plants. They’ll tell me what I can trim and when. Speaking from an indoor perspective, one thing I’ve found is long as I keep a gentle touch, I can develop a resilient plant, that once past a certain stage, the only was it dies other than age is if I ignore or brutalize it.
I believe having a good relationship with your plant is the best guide to defoliation. Trust it to let you know what can go and when.