The maximum number of people varied based on the strength of the Master’s magical energy. Paired with Flat Escardos, it was confirmed to be capable of “dispersing” into a maximum of five hundred and twenty at one time.
Such numbers were of course impossible with both Noble Phantasms deployed simultaneously... but it easily reached over two hundred demons, all attacking the “human” Alkeides.

Fate/Strange Fake: Volume 4, Chapter 13 ("Day 2, Night")