I've been saving a beard for a year now, and it's not any longer than it was after the first two to three months.
The individual hairs are longer, up to around 10 cm, but they just curl up and make the beard thicker. Individual ones may poke out, but then I trim them because it just looks unkempt.
Considering going back to the 10 mm beard, which takes about a week or two to grow from scratch.
I guess that means the beard could have been 20 cm or even more if I didn't trim one hair here, one hair there?