No, you are definitely eligible for the 20 days PTDY with a regular separation. Remember the fine print as mentioned above, and the same goes for terminal leave, that it's CC discretion. You CAN take your PTDY back-to-back with your terminal leave (if approved). As long as your CC is going to give you the full 20 days, just back up your final out date to DOS - terminal leave (you also accrue leave while you are on leave, so factor that in, too) - PTDY = Final Out.