Late Roman Legion size based on the Perge Inscription

[FlaviusB]

the 10 Veredarii could be divided into 5 'file leaders' giving each file 10 men in total and the other 5 are a headquarters.

Yes, that might work if we assume that these turmae are integral to the command of the two-century 'maniples', each under two ordinarii. But it seems an overly complex structure. 

Usually we would expect each subunit to have its own dedicated commander, and that commander to be dignified by a particular rank title and paid more in annonae than the men he was leading. Do you see each individual file operating as its own subunit, perhaps, under the Veredarii?

That would be my guess since the 275 Veredarii appear to be the Legion's cavalry; being able to operate as turmae as well as in their files would allow some flexibility in creating detachments for scouting, screening and delivering messages.