When I employ a DCA.. such as giving myself a weekly allowance, I try to hit the lows within that week... and if the week comes close to ending without my spending my allowance, then I will spend at whatever the price is at the end of that week.  Of course, you can set the days that the week begins and ends at any day that you wish.

From my point of view,  one of the problems with set it and forget it on most exchanges is that they do not let you set your DCA at an exact time, so they end up daily batching them and potentially front running them.  If they let you set an actual time then I would not be against any DCA practice with an exchange that allows for that.