Here's an idea:
Have a card on the table that says, "How did that work?"
Explain that when a player pushes the card toward the GM, the GM has to honestly explain what they just did.
This (1) allows us to work case by case rather than all or nothing, (2) reminds us of an option without mandating when it's used, and (3) allows discussion before commitment (e.g. the other player who says, "No! I don't want to see behind the curtain this time!").