you have to use both methods if you want to create an ultimate phsyique.
by using high rep training you tire/use all the muscle fiber in that muscle group, this will ensure muscular density in the entire muscle. your muscles will tone, separate, and look hard.
by using low rep/heavy training you will only use certain muscle fibers, the dominant ones. this will add size and strength to those dominant fibers only.
either technique is good, but both should be included.
good luck
currently cutting:
wt: 210lbs
ht: 5'11"
bf%: 11%
current cycle:
Off
GU... RIP fallen brother...