Well actually Marks PBF is 5-7x/week move at slow pace, 2x/week resistance training, and 1x/every 7-10 days sprint.
Look at exercise with an eye to the "point of diminishing returns". Every extra workout (above 1-2/week) suffers from this phenomenon. Most people will achieve a very high percent (80-90 as a guestimate) of the positive attributes from just 1-2 intense sessions a week. Is that enough for your goals? It is for mine, but some are competing or looking to still eek out that last 10-20% of full potential. The downside of that is you also raise risk of injury when you try to get every last ounce of potential with a higher work load.
So in the end 2x/week is plenty if your workout is intense enough to reach near your highest genetic potential. If you wanna be elite though, then your not gonna get there with just 2 workouts a week.
I'm a working Dad, with a working Wife, so we share kid duty. 2 trips to the gym a week are plenty for me.