We have an exception to if we are interested in going all in at once with our investment, this could be only possible when we make the necessary research on the previous performances of the market and the coin we are having in mind, then compare the past to the present and if you could speculate something out of it, whereby it's profitable to buy the dip and invest when the market is extremely bearish, in this situation, you can go all in at once and invest, but never make a mistake of investing on anything else aside bitcoin.
Perhaps to be more in a saver side it will be of a great importance to have another separate funds rather than having only one strategy for buying the dip when we know how Bitcoin price movement behave at times and the possibility of falling drastically after moving uptrend is not certain so the best way to take advantage of any opportunities presented by the Bitcoin price is keeping some of your funds on DCA which will allow you to keep accumulating without thinking about if the Bitcoin price is high or not and before you realize you have already accumulated a lot of Bitcoin and the price of Bitcoin may still not be able to get to your targeted point to buy the dip , so perhaps even if you were not able to buy the dip since the price did not give you the opportunity perhaps your DCA has already cover you up.