The signals would not be paired deliberately. There would be an entry signal at each end, and possibly an intermediate signal for each direction, to allow two trains to follow each other in the same direction. The positioning of these will depend on visibility, gradients, speed restrictions etc. as applicable in the direction of travel.
With colour light signals, its probably track circuit block, (no tokens). The location cabinets are likely to be adjacent to signals or at the start/end of track circuits. If cable joints are needed, they can be entirely sealed in a cable joint in the troughing run, no need for a loc.
I feel 4 aspect would be unlikely in the scenario you paint. Watch someone come back with a prototype though!