Centurion Position in Battle

[Mark Hygate]

Are there any indications pointing toward the optios and signifer of the cohort forming their own tent parties ?

P-Hyginus (really our only source for this sort of thing) is quite clear that the century camped together with ten tents for the men and one bigger tent for the centurion. Barrack arrangements were apparently the same - if the principales of a cohort were all gathered together elsewhere they'd need their own special accommodation, which doesn't seem to have existed.

Despite the note above about the optio in the republican legion, I still think that by the empire (at least) both he and the signifer were drawn from the men in the century and messed with their usual contubernia, certainly in the field. They may plausibly have had separate rooms in the barrack, if such were available.

p-H also goes on to suggest that 16 men from the century are on guard all the time and thus only 8 tents are pitched for them and that makes room for the centurions tent! One of his more significant oddities.

Any idea of the reason for the possible change (the bolded part of the quote) by the Imperial period?