Late Roman Unit Sizes

[Marcel Frederik Schwarze]

After this date, while these units may have preserved aspects of their 'barbarian' origins, and may have relied heavily on manpower from across the frontiers and from settled laeti communities, they also took in Roman citizen recruits, perhaps volunteers. In time this 'Romanisation' of the auxilia came to dissolve the boundaries between them and the legions; quite possibly by this point both sorts of unit had come to have a generally similar size anyway.

Well then. I have nothing more to add. Looks like a fluent process.
In their development those units tried to be similar to the cohort or legion (or it was imposed to them) resulting in a similar (!) ranking scheme with centenarii, ducenarii, senator (+primicerius?) and tribunus. And what about their unit size? What happened if a tribe has sent 800 men, another tribe just 350? Was the great unit (800 strong) halved? Or did the Romans always demand the same number of soldiers?