A 7-minute workout isn't really going to accomplish much, but the original paper suggests repeating the 7 minute program multiple times per session.
This article is attempting to repackage old knowledge, but that doesn't really mean that it's a waste of time. There are world class athletes that use only bodyweight exercises to stay in shape. Going to the gym and picking heavy things off of the ground isn't a strict requirement of lasting fitness. Weightlifting is a perfectly viable method, but it isn't the only way to get in shape.
This article is attempting to repackage old knowledge, but that doesn't really mean that it's a waste of time. There are world class athletes that use only bodyweight exercises to stay in shape. Going to the gym and picking heavy things off of the ground isn't a strict requirement of lasting fitness. Weightlifting is a perfectly viable method, but it isn't the only way to get in shape.