Lookouts, sentries, and guard-duty

[Devonian]

Has anyone tried to put an estimate on the number of bodies that would be needed to fulfil the roles of Lookouts; Sentries and Guards?

Given that you may need guards/lookouts etc on the perimeter at say 4 (or more) different points, and even then do you need more than one person at each point; plus then at least one person back at/in the property etc to rely communications and to warn the others who are not on duty at the time.

Then how often/how many shifts are needed throughout the day/night? 2 hour shifts for example have been suggested.

So with 4 points with 2 people, plus one in the property, means you have need 9 people per shift, based on 2 hour shifts over say just 12 hours of the night means you need 6 x 9 people = 54 people!!

Even if you only had just 1 person at the 4 points plus 1 in the property, with each working 4 hour shifts, within a 12 hour period, you would still need 15 people just to manage your overnight guard duties!!

So this quickly adds up to a lot of people if this is to be carried out day in day out.

Therefore is you want to be able to operate with guards and sentries etc, you really are committing yourself to operating within a "large" highly visible group.

Maybe I'm looking at this in the wrong way, but I'd be interested to see what resources others feel are needed to set up a workable system in this respect.