I'm not sure where the "no days off" fad came from. In order for your muscles to recover and grow, they need downtime. If we were training like bodybuilders, we could let one muscle group rest while we trained another. But because we're working the whole body every time we train during Charlie Mike, rest days are a must.
If you're consistent with your nutrition and don't use rest days as free-range days, you won't see any backward progress in your physique or your performance!