I do wonder, what number of 7 minute workouts per week is appropriate? I'm clueless, really - I've heard that you should not work out more than once in two days

I do wonder, what number of 7 minute workouts per week is appropriate? I'm clueless, really - I've heard that you should not work out more than once in two days, and to me it does make sense to apply this rule here, since it advertizes itself as full workout. But yeah, I'm not really sure - it would be great if someone could elaborate. PS The site is great - simple but very useful.