This is only a good method if you're aiming for long term, if you put your money that you'll be needing soon then it's not a good choice to buy BTC. Cause if you want to a quick flip that you could profit instant then buy and store is not recommendable.
You are right. Keep buying Bitcoin any time and never caring about the price are okay for long-term investment, but it is not an effective way for a shot term investment or trading. Not each person buys Bitcoin for a long-term holding, some people just buy Bitcoin for short holding or even trade Bitcoin weekly or monthly. Also, if we can analyze the right time to buy Bitcoin, why we must buy at any time? Not every time is a good time to buy, just buy whenever the Bitcoin price goes to the dip (low price). We must optimize the chance to earn higher profits, don't buy carelessly.
You are right, but then, how exactly does one know when the price of bitcoin is at its deepest deep?, this is an important question that I believe have no definite answer, simply because, the only time we can be sure that the price of bitcoin or any other crypto coin is at their deepest deep is when the price is at $0, which is realistically not possible for bitcoin, and any other major coin that is already being traded in the open market.
What I would say here is, just buy when ever you feel the price is OK for your, cus price of bitcoin is most of the time not stable, the price could be going down, and you wait for it to go down the more, only for it to start pumping up in the next minute, this has happened to me on several occasions I wanted to buy bitcoin but was looking for the bottom price.