Do you like to change mobile ring tones?

While I don't change my ring tones that often, I do have a lot of pre-sets. I know when my mother calls, for example, before I even look at my call display. I have one standard pre-set that lets me know when someone who is not in my phone book calls, and that's when I look at my call display. If I changed my ringtones, I'd get completely confused.