Originally Posted by
al613
They can limit it to discounted fare classes, like N on United and 7 days in advance you will not find any availability on most routes.
Exactly. Or they could even limit it to E on DL, although I think that has advance purchase requirements of something like 21 days. So then you would have to book these tickets more than 7 days in advance.
Also, various discount classes earn little or nothing when credited to partner FF programs.