You can accept appreciation without signing up to perform the same favor forever.

Being thanked warmly creates a small debt in the wrong direction. The gratitude was for something you chose to do once, yet it can feel like an agreement, so the next time the need arises you say yes partly to protect the good feeling rather than because the room exists. Appreciation is payment, not a subscription.

When thanks arrive, receive them fully and let that close the transaction. If asked again, decide on the merits of this week instead of on the memory of being appreciated. Saying you cannot manage it this time does not withdraw the help you already gave.