I have only received 3 so far, from a default of multiple accounts in 2008. Only from OCs. In 3 different years. Two were business accounts.
There doesn't seem to be a pattern of predictability that I have seen.
Edited to add: all 3 were for relatively small amounts, well under $5K, so I just added them to my 1040 return as other income. I didn't bother with Form 982, as addition of the 1099C amounts did not change my tax burden.