If you are having a long-term mindset then no strategy is to be regarded as useless because you have time to grow your investments over time. It all depends, according to your financial power which gives you the leverage to take decisions that aligns with your sole aim and investment plans either DCAing, ump-suming, buying during dip are all good strategies. But the only thing that is to be considered is consistency matters a lot when investing for a long term of which DCA is more of good advantage and effective than other strategies because you're always accumulating bitcoin steadily and gradually either weekly or monthly without timing the market and without purchasing a whole Bitcoin or without a bigger amount but doing it at your comfort
All planned strategies are counted as effective if they are long-term and consistent. All methods work but for a newbie like me I prefer DCA. Because it is more simple method and I find this method more effective method than other methods. Because adopting other methods requires knowledge and courage to make bold decisions. When do you buy? How much to buy? Not everyone has the knowledge and courage to make these complex decisions. But the DCA method does not require any complex decisions and much knowledge. You will buy a certain amount regularly, which will depend on your earnings. If your income is higher, the amount you buy will increase and if your income is lower, the amount will decrease. There are no complex calculations and no price implications. After holding for a long time (4-12 years or more) you can decide to sell or go long if your target is reached.