Yes, I'd say my H took at least 6 years to work through his issues.
It's interesting that your T felt that the more damaged the man, the longer the journey. In addition, I've read that a certain amount of self-awareness shortens the journey: the man who recognizes that HE's depressed and is able to reassess his life at its midpoint may be satisfied with a motorcycle, changes to his routine, etc. However, the guy who can't take responsibility for his feelings blames the world as he refuses to entertain any thought that his unhappiness comes from within rather than without, and so is swept kicking and screaming into a very deep depression.
You say your H was always a weak man. I came to the same conclusion during my H's MLC ("Why did I never notice he was so weak? Or so selfish?"). In retrospect, however, I think these traits became much worse during his depression. And one of the ways I became sure that he was recovering from his MLC was that he became stronger: readier to put his own needs and the needs of his family first, able to stand up to his manipulative boss, etc. Even apologizing for hurting me so deeply during his MLC was a sign of new-found strength, as was his greater self-understanding.
Do you feel your H is and will always be weak, or has he demonstrated any growth? Also, has he come to any resolution on his feelings towards his mother?
