I never understood why FaceID is enough for some parts but for other parts you suddenly need the Passcode like why? Is Apple implying faceid is less secure than a 4 digits passcode?
It’s required once at boot to unlock the Secure Enclave where Face ID data is kept. Also if the phone has not been unlocked for a long time (> 48 hours) etc. There shouldn’t be too many other places where it’s needed?