I have a friend who recently told me he had received 8 buddy passes on his anniversary date. Believe he has been with Delta 20 plus years.
As I understand, the passes carry an S4 boarding priority, meaning you would be one of the last to clear the stand-by list.
I was on a late flight from ATL-DFW in February, overheard the gate agent say that First Class was filled with "buddy passers". As a PM flying on an L fare that night, I did'nt have the luxury of standing-by for First Class. Of course on the other hand, there has been many times I have seen stand-bys left behind because space was not available.