For me, it was: “If it’s going to help your players have more fun, cheat. Fudge a die roll. Make shit up. The dice don’t tell you what needs to happen, your players’ reactions do.”
Obviously, many people will disagree with this, but I’ve always appreciated this advice, and I believe it has made me a better GM.
I don’t like that advice. Part of the fun of TTRPGs, to me, is the randomness involved in outcomes.
But if it works for you it works for you.
Best advice I’ve ever gotten was that the DM isn’t responsible for everything. So now I let players handle the scheduling.