One excuse is a bad day. The same excuse every week is a policy.

Anybody can miss once, and treating a single lapse as a character flaw is unfair. Repetition is different information. When the same reason turns up every week, it has stopped describing an interruption and started describing how the thing actually works. That applies to other people and to you, and it is worth knowing without treating it as a moral failure.

If you hear yourself giving the same explanation for the fourth time, take it seriously as data. Something in the setup is not working. Change the setup rather than promising harder.