I understand and appreciate all who prize the image enough to not take the chance with the developer.
On the other hand, I figure now (as a beginner) is the time to test the limit and find out the answers to all the little nagging questions.
So, what I found out this time, is that 16 oz of diluted DD-X solution at 1+4 a day after the first 4 rolls (2 rolls per batch/tank, twice) can at least develop 4 more rolls in the same way. (2 rolls per batch). I stayed within 24 hours of the time the solution had been mixed. I did slightly increase the development time but not much more than 30 secs.
I developed 2 rolls of Tmax 400 first today, and then 2 rolls of Neopan 400. I would have reversed it as the pink dye of the Tmax always freak me out a little.
Thanks all for your replies! I think I got lucky today.