For example, the stress on the muscles of your hips and legs from walking is TOTALLY different than training with loads that allow for 20 reps. There is no comparison, and yet you made one stating the somehow walking made your legs accustomed to high reps?
In terms of hypertrophy, there is a definite correlation between pumping types of exercises (those which give you a pump and result in a heavy buildup of lactic acid) and growth. A solid 20 rep set of squats will definitely pump your thighs. In a nutshell, 20 rep sets for legs are good for growth both in beginner and advanced trainees.