Do 7-minute workouts work?

Life can often get in the way of a consistent exercise schedule. Is the classic 7-minute workout a legitimate substitute for gym time?
Yahoo

No equipment, no repeat exercises — this 7-minute core workout sculpts the abs and obliques

I wholeheartedly subscribe to the idea that anything is better than nothing when it comes to working out, and have found that if you're training consistently, even doing just five to 10 minutes of ...