I find its very much dependent on space
plants that are free to stretch out and receive light from all directions will unlikely need any foliage removed
sativa structured plants are ideal for this
growing 2 plants both in an open space and picking leaves off of one of them is a pointless defoliation test
i would assume the defoliated plant wouldn't produce anymore
however if you have a number of plants, or a single plant with multiple colas which occupy the whole grow space where shading of lower branches and leaves is unavoidable
in this situation removing selected foliage, branches and leaves can give a great boast to the overall quality and yield
it will allow growth to flourish at the tops where they have access to direct light
i think leaf removal should be practiced with caution if needed in tight spaces
but should not be separated from other forms of pruning/training like its some form of voodoo lol
those with enough experience know it can work well, although to be fair there are often alternatives as some will suggest, like bottom lighting, tucking leaves under, etc
removing any part of the plant leaves or branches is a form of training/pruning
some work well some not so well, live and learn !
peace