I have been training for the past 10 years, from 13 to 23, but never with a focus on hypertrophy. My first few years were in calisthenics. After about 7 years of that, I switched to weightlifting with a focus on strength and I trained like a powerlifter. During this time I never monitored my protein intake. I put on a good amount of muscle, being at a BMI of about 27 when my bodyfat is in the low teens. Now I intend to switch to a hypertrophy-focused routine and consume the appropriate amount of protein. Should I expect to see a significant amount of muscle gain, given that I have been training for 10 years now? For example, is it possible for me gain 20 pounds of muscle in the next 10 years assuming average genetics?