This calculation is way off. It assumes that, since it takes 5 seconds to pick up a penny, you could pick up 720 in an hour. Try it. You’ll be huffing and puffing after about 50. Try bending over and picking up a penny 720 times in an hour and you will be in the hospital.
I can pick nits though.
A big welcome to you, clarencex! 
When starting a new thread in this forum, we ask that you link to the article in question. This used to be more difficult; now you can follow the relatively easy step of clicking the “add link” button on the tool bar just above the text entry window. In this case, the thread would be: Is it worth it to pick up a penny?.
As to your picked nit, I’ll note that Unca Cece answered the question asked, which pertained to one penny only. The answer didn’t assume you’d be doing it over and over. Presumably, if you had more than one to pick up, you’d stay bent over, much like the lettuce cutters and strawberry pickers do.