tementaXCD

I was just wondering whether this is true are not. Experts say that if you want to develop more muscle you should use smaller weights and more reps but for more mass you should lift heavier weights and less reps. Let's say for each week, on Monday you lift small weights for more reps but on Friday you lift heavy and lift less. Would I be able to develop more muscle and gain mass at the same time.( this only pertains to biceps and triceps, on Wednesdays I would work out abs so no lifting involved)