Changing my weight lifting program

My roommate recently learned in his class to switch up reps. Instead of doing 10 reps of as heavy as you can, try a little less weight and do it around 20 times. He said to do it for a month to shock the muscles. After a month goes by, I can go back to my regular workout. I'm pretty excited about this. I'm going to give it a try and see if I can get better results.