The games were alot shorter back then, but people generally played through them multiple times. I remember my baby sitter had a copy of Duck Tales for the NES and one of the older kids would beat it once a day for like a month straight. He was a fun guy; he let a different kid play the final 'race' against Glumgold everytime so technically that kid 'beat' the game.
I wonder; do kids today re-play games very often? I know I don't but I foolishly became an adult at some point and got really into my hobby of paying the rent every month.