As a note, RAW in D&D since 3rd edition is a Nat 20 is only auto success in attacking and the same with Nat 1.
The idea of Nat 20 and Nat 1 being auto success/failure in skill rolls is a frequent house rule, but it has never been RAW.
That said, the general rule of GM etiquette is "if 1 can't fail or 20 can't succeed....don't make them roll."
Very true. That said, sometimes players insist to do something even if you advise them against it
Or dont catch on to the fact that they shouldnt be trying to stab the dragon that is actively trying to save their life.
Or attack the avatar of a god when you expressively told them it is the avatar of a god.
Yeah...some of my players are idiots xD
