I realize that this is an old post, but this issue came up for me in a recent grow, mostly do to overcrowding in an indoor space. It has always been my experience that with two polarizing opinions, the truth almost always lies somewhere in the middle. Some people like to prune all the way through the plants life cycle, some swear that you should never do this. I have personally seen excellent results using both techniques, and think they both deserve merit. I personally do modest foliage removal, and some lesser bud removal all through the grow. This is largely based on my previous knowledge or grape growing, where much of the plant is cut back over the growing season, to encourage only the best growth, removing all fruit and leaf, that is either to small or poorly positioned. I think that this same mentality should be applied to marijuana. I believe that is is best to do most of the heavy trimming before flowering, but some surgical extraction of week buds, or extraneous leaves will only help your grow in the long run. Once I move into late flowering, I do tend to start to drop a bit more of the middle and lower leaves, always with good results. Late in flower once the buds have lots of good sugar leaf all over them, I feel like it does more for the plant to get more light on the buds at that point, and not the fan leaves. I would challenge the people here arguing counterpoint, to actually try it the other way before dismissing what could be useful information. In conclusion, most of the successful, high yielding growers I know almost all advocate for a certian amount of defoliation during all stages of the grow, some do a little more that others, but all of us do some. Your room, lighting, strain, and level of overall expertise are more important factors than clipping a few fan leaves anyway, a good grow, will be a good grow either way, and some good pruning(or lack of)won't turn a bad grow good.