just so we don't sound like robots and mere perfect people, The DCA method is obviously good and being consistent with your strategy will get you to your goal within the fastest possible time but let's not forget the reality that as human, there might be weeks or month issues can come up and maybe you might miss out on your accumulation routine for the month. As long as it's an unavoidable situation, you've got to be realistic enough and fix your issues and continue with your accumulation routine. The DCA strategy is not to enslave you to your investment and close you out of life reality. You've got to strike a balance between your investment and your real life issues.
I don't think this is an excuse, definitely we are humans and humans are bound to face challenges especially when it comes to money, challenges should not be an obstacle when investing if you plan properly. That's why it's advisable to set aside some funds for emergency (Emergency funds), if having an emergency fund during such time it can be of help rather than stopping your accumulation process. When I first started it was difficult cause I had no planing idea and no emergency fund, I just buy and buy without a plan and it was difficult honestly but when I started this learning process I knew it's best to include emergency fund when planning.
Also, the assumption that the DCA methord is the best isn't all that correct. The decision to buy using the DCA methord or to do lump sum starch is totally based on your financial strength. as long as the methord you're using is working well for you and will help you meet your goal within the shortest possible time, that's the best strategy for you but that's not to suggest that it's better than buying in lump or that its more profitable than bulk buying. Buying in bulk during the bearish season could put you in a better profit and would normally save you from whatever issue that might spring up with time by using the DCA methord.
Just stick to what works best for you based on your financial prowess.
Shortest possibly time with bitcoin investment is not advisable except the person what to gamble with his/her investment. Bitcoin investment should be a long term investment plan, I will buy using the DCA strategy cause it suit my income, I don't think if it's the best or not but I think beginners should not get involve with the lump sum strategy but rather the DCA strategy.