I use to trade in short term. I choose a coin which have regular predictable waves (+-20-30%) and set buy and sell orders on the bottom and top of these waves. And it most cases it works for me. I also tried the strategy that you described but it's applicable only for a long term trading.
I agree with this strategy and style mate. I also choose to trade short term by setting up a gain of around 20 to 30 percent. At least that way, I do not have to wait for too long to see where my investments are going. Unlike for other ventures where it takes a long time that you are somehow left hanging, not knowing if your investment would do you good or not.