But what about the volume and intensity? There have been studies where light weight gained just as much muscles.
But really it's getting the body to adapt to something new.
As far as the training, I would up the frequency .For example Biceps 2-3 times a week.Same with chest ,legs etc. But keep the volume the same.
Not much volume is needed really.Just enough.
And stick with compounds.
I am assuming you do a lot of iso exercises considering you dedicate a day to just hams and glutes?