theres a difference between "need" and "optimal"
right now im training the way most top professional bodybuilders would tell you to train. i go untill i feel like the muscle is as full and stretched and as beat up as possible.
secondly i would advise anyone who would doubt the effectiveness of a high volume routine to read up on how exactly training triggers muscle growth. and if your one to just listen to the theories of others wich are based on no science (mentzer, yates, etc)....well, learn some science. at the end of the day the science shows that you beat the fuck out of muscle as hard as you can, and thats what makes it grow.