Why do you have to let the crepe batter stand for 30 minutes?

Letting the crepe batter stand for 30 minutes allows the flour to fully hydrate, which improves the texture and results in a more tender crepe. This resting period also allows any air bubbles to escape, reducing the likelihood of holes forming during cooking. Additionally, it gives the gluten time to relax, making the batter easier to spread and ensuring a delicate, smooth crepe.