I record endurance use.
I use dice.
But it is not a house rule.
So, if you have say 28 END and use 4 END on average in a phase, you get 7x4-sided dice. You can always look at your dice and see how long many phases of action you have left. As a GM this comes in handy if there are a lot of superagents around. I just ignore the actual END and use those dice, you use 4 and have a 5 rec, and you get "1" die back. Mostly accurate, but you do not waste too much time doing math or writing things down.