Being a full body exercise I am sure some endurance and cardio benefits would result if the squat sets had enough repetitions, beyond that it is just a numbers game. If it gets them to workout every day there is that benefit also. I see one problem, I doubt that the ones doing this challenge are doing proper full squats, most likely only parallel squats. Best way I know to overstress the knee joint.
It is called WORK-ing out for a reason.
I said getting fit was simple, I did not say it was easy.
Cardio burns calories, strength work burns fat.
Eat well to lose weight, exercise to get fit
You can not build a six pack using twelve packs
Often when we seek a magic bullet for fitness we end up shooting ourselves in the foot.
"I think calories are little germs in food that all moms are afraid of" Dennis the Menace