What "best practice" rider doesn't look backwards at least every couple of minutes?
This is really a discussion for another thread but....
While riding do you also keep looking down at your drivetrain to check which gear you are in, or checking your trouser zip to make sure you are not 'flying low'? Of course not, because while on the move, especially in traffic, you have your eyes on the road and road users around you (in front and behind). Looking down at your rear lights every few minutes, or a couple of times a minute if checking every time you look behind, is a bad idea and as advice goes is neither safe, sensible or practical.
Sure I do occasionally check my rear lights while riding, usually because I have a 'Did I actually switch them on?' moment shortly after beginning my 30-40 minute commute, but this is not every commute, maybe 1 in 5? I will also maybe check them once or twice during longer darkness rides, but they are very reliable with a long run time so this is not essential, besides I have two lights so if one fails I am still covered.
In my opinion the following is good advice;
Run two rear lights, either of different types or one flashing and one on constant (always the same ones). This way, even if you tend to charge them both at the same time, they will run flat at different times and avoid you being caught out with no working lights.