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.
The best trading strategy, risk-profit is the long term on. Short term trading will just make it impossible sleeping at night.
The best strategy for trading you must always monitoring the graphic movement of cryptocurrency.When the value of crypto coin was getting low just sell it and then when its get hight just buy crypto coins which have potential to grow.