Is true that defoliate and or pruning increase the yields?

No..........less leaves (defoliation) = less energy production = less growth. Better to do nothing............the plant knows exact;ly what to do! Have been growing outdoors for 40 years now and for the last 25 years just let them do their own thing, but I do believe in some well considered "lollipopping". However, I am convinced that defoliation id bad. Have experimented extensively with pruning, but again, for the last 25 years or so, do not prune anymore, I believe it causes more disruption than rewards. A bit of LST is always great, but never defoliate and never prune seems to produce the fastest growing and happiest plants in my experience. Pruning and defoliation seems to me as though man is trying to force his ideas as being superior to Millenia of evolution, whereby cannabis is at the peak of efficiency already. Sunlight, healthy soil and love will produce better results than any sort of plant torture techniques (defoliation/pruning) in my opinion.

It's definitely true my friend! When you defoliate you're clearing away areas that would have been covered with shade and are now going to be getting sun light. You don't want to clear away too much though as leaves are still necessary for photosynthesis but you do want sun light to hit those flower sites. Hope this helps