Avatar Etiquette?

I'm just wondering, are you a user who changes their avatar frequently or are you the kind that sticks with one and carries it with you until the end of time?

I say this because I have stuck with my Bob the Painter-

-since near the birth of this site, but recently switched to Joaquin Phoenix-

In other words, is your avatar something you consider a part of your identity or is it something you change as often as your underpants? I tend to be someone who likes to stick with an avatar and tends to identify others by their avatars, but I'm not above a little spring cleaning, powder, and a little freshening up.