you asked what works best and I can tell you that in my experience defoliation (removing 10%-60% of MATURE leaf material) is absolutely necessary from time to time and even sometimes on a regular basis....
allow me to explain... and remember all I said in MY experience. Thnx.
I have vegged some of my plants for long periods of time and generally grow plants on the larger side. I find that the plants are healthier, more vigorous, and more able to handle neglect. I suspect that a more mature plant is more capable of creating quality bud. It is a hunch but i bet if you ask just about anyone who has vegged longer than 2 months (indoors) and they will likely tell you that they defoliate to some degree. It is a natural part of the plants life anyway right?
That being said I could see growers killing or injuring their plants if defoliation is not used properly. It can actually be a very effective way of murdering your baby if you got carried away.
All i am trying to say is. Defoliation is a useful technique that should be understood and available to all growers. I find it effective for lst, pest control, dealing with rich soils, light penetration, bud development, air flow, slow growth down. etc. etc.
Some leafy strains I may defoliate twice. Once in veg and another light defoliation 1-2 weeks into flower depending on things. I have not had as much success with defoliation on Sativas and I strongly recommend not defoliating sativas much at all. They just really dont seem to need it or react well for me so i generally leave them alone. My grow environment has always been hard on sativas though.
Now i have fallen back on defoliation as a technique to help with the way I grow (certain strains). Others find other ways of dealing with the same issues I am sure. Others use chemical fertilizers, or Others also do not veg anywhere close to as long as I do and any defoliation for them would likely result in a setback... not necessarily in quality or even yield but in the time it takes to get there. I am not a commercial grower so I can afford to wait for my ladies.
I like short flower times as much as the next grower but defoliation is necessary for me to manage my perp grow and get my plants the way i need them.
I dont know about the rest of you but my flower room gets crowded and there is a line to get in there. Defoliation allows me to slow their growth uniformly while the root system continues to strengthen before flower. They enter flower looking squat but robust and ready to work.
I gro organic with soil.