Running a 20 pound tank on a single stage reg and a 125 gallon tank makes me worry less about the EOTD thing. It is possible to get into trouble but it does seem to take some lack of attention to do it. First thing is how close you are to gassing the fish under normal load. If you are running close, a small increase may push it too far.
But understanding how to avoid that small increase is the better way for me. I just work carefully to make sure I don't leave a leak so that I lose a tank of gas. Seems logical to take a few minutes to do a leak check to avoid the hassle and expense of losing the gas. If I don't get careless and lose a tank overnight or so, the next thing that can create end of tank is running down to that point.
I have something like more than a week to notice the gauge beginning to move down as the last of the liquid has been used. Somewhere along the time when pressure comes off the normal and when it get down to 400 PSI or so, I find time to refill the tank.
If you get silly and don't take care to check and watch your tank, you may pay the price.
Kind of like driving, if you don't pay attention, you may have to pay the price but it's easy to avoid.