I would track it over a sensible period rather than try to make every individual match identical.
Children get tired, arrive late, miss weeks and sometimes need a little break during one particular game. So exact equality every Sunday is difficult.
But the parent should still be able to see the principle. If one child repeatedly gets the shortest time whenever the game becomes competitive, saying “it balances out somewhere” will not feel convincing.
A simple minutes record across four or five matchdays can help coaches spot patterns they may not notice from memory.
I’d explain that equal opportunity is the aim, not a stopwatch-perfect split in every fixture.
And if one week is noticeably lower for a child, I would try to correct that naturally in the following match rather than waiting until the end of the season.
