Which technique do you think is better for a gym goer - Lifting heavy weights to gain mass OR lifting light weights and doing more repetitions to gain mass?
See, if you want to gain dense muscles and In minimum time,them lifting heavy weights will help you out ....
Now ,let me tell you the science behind heavy weight training. Since heavy weights are mostly lifted in compound exercises like Squats, deadlifts,bend over rows, military presses, bench press,barbell curls etc... Now a question would be coming in your mind, what are compound exercises?
Compound exercises are those exercises which uses more than one body part to perform that exercise or technically they torture more than one muscle group. For example, deadlift ( the king of all exercises) uses your lower back,trapezius, hamstring,glutes, latissimus dorsi,forearms and last but not the least your biceps muscles.
Now , when these kind of exercises are performed,they send a signal to your brain to release more growth hormone and more testosterone which eventually helps in building strength and muscle mass. It makes you feel like superman.
In conclusion, I would go with heavy weights in compound exercises and this is scientific proven way to increase muscle mass in minimum time.
It also depends upon your previous training methods,as shock principle is used to shock muscles and grow them..... Hypertrophy is also good for muscle size but if you ask me for best then I will put my money on heavy weights.