Everybody has their opinion on this issue. Some defend it, others condemn it. My personal take on this issue is that there are definite trading environments in which scaling is the best way to ensure that you have exposure and flexibility without necessarily increasing your risk exposure. At other times, there is a true opportunity cost to trying to get cute with the entries and prematurely taking exits. Right now, late April, early May, there have been a number of sessions where the best path has been to simply enter all at once and wait till your target is hit. In other words, I think the movement is "cleaner" now than it was say in any time between the end of January and the middle of March.
At that time, many were frustrated with the lack of follow thru, the dominance of the programs and the overall skiddishness of prices. I believe scales work in an environment such as that when you have such a great level of "noise" and so much chop between levels that you want that extract flexibility to average the cost. One could also argue that those are times not to trade at all, but since we are talking about basically trading on a daily basis, that is an adjustment that I think has merit...