The batter wants resting for at least half an hour, which lets the flour hydrate and the bubbles settle, and it's the difference between a crepe that tears and one that doesn't. Chef Emily built that into the session rather than pretending you can skip it — the creme anglaise gets made during the wait. That custard is the part worth learning properly: constant stirring, off the heat the moment it coats a spoon, and absolutely no boiling or you have sweet scrambled eggs.
Elias