As my readers know, I like to buy stocks when they have a GLB to an ATH. Once a stock has a peak that is not surpassed for at least three months I draw a new green line. This monthly chart of AAPL shows 3 GLBs where it would have been profitable to buy AAPL. Now that a new green line as been drawn at 182.94, I would not buy AAPL until it breaks above that green line. You may think that you should buy it much lower. But you never know if a stock can climb back above its green line, until it does. Check out AAPL and then MSFT to get the point.
Once MSFT formed a green line top in 1999, it took until 2016 for it to have a GLB. That is a long time to wait for a stock to come back when one could have instead bought other stocks having a GLB.