Place 80% of the men who play the game today at a max of 6,500 yards and they'd likely be quite content.
Few women should play a layout that's more than 6,200 yards. Both yardages assume sea level altitude.
I assume you mean that most of them should play a course that shorter than those numbers. Because if you mean that 80% of men would comfortable at 6,500 yards, you need to get out and play with more "regular' golfers
I play with a fairly broad spectrum of adult males, ranging from scratch to 25 handicappers, and ages from 14 to 80, and there are no more than 10% of them who can play 6,500 yards and enjoy the course.
I am a 62-year-old 12 index which puts me above average for scoring ability. I hit it about 210 off the tee, and can manage no more than 165 with the club that would be my five iron (a 30* eleven wood), so any hole over about 375 ends up being two fairway woods.
My wife is a 14 handicap, and has been in the top 10% of women at every club she's played, and she HATES playing anything over 5,200 yards.