I agree, in my playing past, some of my mates were playing three games over a weekend including two, in the same day, I could never do it but a few did.
It might seem ridiculous to compare full time, pro football to amateur players but the basics are the same as is the physical effort. I used to come off the pitch, unable to walk some days after playing 90 mins and would joke with my mates that they can't have given their all if they could play another game at the weeekend.