From Agfa's instructions (pdf file, 2003)

One-shot developer: with 500 ml concentrate about fifty films
(135-36 or 120 roll-film) can be developed.

Although one can get away with less, and I'm sure there are variables, such as how much contrast you need, 10mL per unit of film isn't extravagant. I've always wondered what the difference is between attaining a certain contrast level by exhausting very dilute developer, such as 3mL to 5mL per film, and attaining the same overall contrast with more developer by limiting the dev time (same concentration, more volume).

Incidentally, Agfa's own dev times were for pretty robust contrast (gamma=0.65).