Parks usually wears two, Lyman does from time to time. Both of those guys have had both knees operated on.
Vandall wears two most of the time, but I've heard he's never had a knee injury and wears them for preventative measure. Anyone confirm?
From what I've seen, most guys wear them for the season following injury, then eventually shed them. Greenwood, Watson, etc... Although Shane seems to always wear his.
I guess I notice this a lot since blowing my knee. I wore mine all this season (1st year back) and will probably continue wearing it next year.