Codes that are provided on demand by a service will always be far less secure than proper TOTP. Because in the case of proper TOTP, no secret ever leaves the se

Codes that are provided on demand by a service will always be far less secure than proper TOTP. Because in the case of proper TOTP, no secret ever leaves the service after initial configuration, but in the case of discount 2FA through email or especially SMS, a fresh secret has to be delivered to me each time, where it can easily be intercepted by all manner of attacks.