True but mostly when you're trading valuable coins like Bitcoin and probably some well known altcoins (but this isn't a guarantee). With altcoins that aren't popular or having low trading volume or exposure compared to their counter part, the chances of using this strategy and come out profitable is minimum.

Just as you hold and wait also note that sometime you profit more or lose less if you were willing to take that small lose, wait for further dip to re-enter the market or move on to other opportunities. My advice would be to always take profit when the opportunity presents itself don't forget you're trading and not investing.