No one was suggesting to go hard every day. The suggestion was that "no zero days" is a good way to build an exercise habit.

The OP comment was pretty specific and explicit that it is not going hard every day, it is about doing some minimal something every day to maintain and reenforce the habit. You asserted that you “explicitly require some zero days” but that is not true. You can have no zero gym days by using your heavy lifting rest days to do mobility exercises and stretching.

What are you basing that on? Elite mobility coaches like Kelly Starter recommend daily - even hourly -mobility and stretching workouts, with the goal of being constantly mobile.

If you're damaging the muscle while stretching… Okay, I'm gonna assume you're not letting any of you're stretches produce pain. You should feel tension, only, which should not be harmful.

In my experience and training, stretching every day is practical and effective. Skipping a day can cause noticeable tightening. Tension for the purpose of becoming more limber should be held for a minimum of 10 sec, but 30 sec. is a much better basic level. There should not be tremor or pain; either of those will be counter-productive and potentially result in injury.