The various types of missiles would've had different requirements. I know that the Titan II missiles had 2 officers and 2 airmen manning a launch 'capsule' for each silo. They were much more high maintenance due to the liquid fuel.

The Minuteman system was one answer to the maintenance solution and uses solid fuel. The areas I refer to as 'sectors' relate to designated flights of missiles. Each 'flight' has a letter designation for 11 facililties. The first-numbered facility is the Launch Control Center and this would be the only regularly manned point for those 10 missiles. I have to be careful to say 'first-numbered facility' because some flights start at '0' and some start at '1'.

You can see the difference between the two types of facilities by looking at the Malmstrom AFB missiles in Montana. Look at I-1 and then look at I-2. (they're also labeled of course as to what is a control center and what's just a silo)

The silos are connected to the Launch Control Center via a buried 'hardened' cable. There are signs all over the place there in an attempt to warn people who are digging or plowing. Stories are told that farmers have managed to cut those cables from time to time.