Or, ideally, some general settings for each position's substitution patterns -- nothing like setting exact minutes, but maybe:
Keep him in!
Use Coach's judgement
Rotate them.
That would help people who want to force the player to stay in for training purposes and those who want to make sure their backups get more than 5 minutes in a game for GS purposes, but have a starter with too much stamina. The fact that the phrase "too much stamina" exists is really all we need to know.