Buying the dip has been a golden opportunity of buying more of a coin with the same amount that would have given a lesser amount of coin from it's previous high although, it shouldn't be seen as a primary strategy for accumulating Bitcoin but it should be a secondary strategy without over doing it.
I think there are many strategies in buying bitcoin. Buying more is currently the main strategy or you could say the main goal of someone in accumulating bitcoin. But you can't predict the market. Because of this, there are many strategies for accumulating bitcoin, such as short-term trading, futures, or DCA like what El Salvador does.