I can only speak for my own experience from letting my beard grow out a while back.
It took eighteen months to get to what you see on my avatar. Although I enjoyed ownership of it at that length, it was a responsibility which I felt would wear on me over time. It isn't so long now.
You don't really want it much longer than that anyway else it gets caught up in stuff. More importantly, people don't realise what a fire hazard a long beard can be.
As I am otherwise quite bald, what I learned from the experience was:
I rediscovered the joy of being able to run my fingers through my own hair.
I rediscovered the thrill of feeling the wind in my hair.
Little children thought I was awesome
Older people thought I was a dirty old tramp
Oh, and when I trimmed it back to stubble I had the extraordinary feeling of wet skin where there had previously been hair. It wasn't actually wet but I still had to check in the mirror a couple of times at first. That took a day or two to get used to.
Mr Sklar is therefore both my bass hero and my beard hero.