Whats the best training to gain lean mass

I can train 6 times per week, so I wonder if the best way is to train a single muscle per day, or two muscles perday 3 times a week.
Or even it could be two muscles per day 6 times a week.

Another alternative could be all the muscles in the same day, 3 times a week, so all the muscles have 48 hours rest.

Opinions?

Are you a noob or advanced.....

4-5 times a week is all you need.... 4 is fine

There are two options I push...

A 4 day power/hypertrophy routine where you train the whole body 2 times per week (power and hypertrophy session for both upper and lower body)... This is great for naturally guys or noobs IMO... However everyone would Learn about basic progression and fundamental traing techniques with this program...

Or a 4 day High Intensity Routine.... Where the whole body is trained over a week period only once.... This is more of an advanced training routine that I would not recommend to a noob or even people with a few years under there belt...