“Buy Low Sell High” is a useless strategy unless you have a crystal ball at your disposal. Of course we all want to buy low and sell high!
On the other hand, if you set a strategy to “buy high, sell higher”, now you can look for ways to ride along a curve and make gains in the middle of ascending gains (price increase) when the stock is moving up higher.
In the same vein, if you set a strategy to “buy low, sell less low”, you can look for ways to ride down a curve and make gains when the stock recovers (price drop then price bounce-back) when the stock is fluctuating. Keep in mind, however, that buying a price drop can be riskier because you aren’t sure whether you are close to the bottom or nowhere near the bottom.