Im not sure when it was you retired, but its not at all uncommon for the site to be linked via microwave to either a central node or as part of a trunk off an adjacent site running modulations of 256QAM+. I see coordination notices by the hundreds at the office anywhere any of the carriers are constructing and there is a chance their microwave operations could affect mine. Same goes for the building.. It is completely finished inside and out: HVAC, cable trays power distriubution, lights, even a common ground buss with attachment stud outside. As i said, just add power and radios. I know, I've bought two for our own use as repeater sites.
You are correct that a week is silly and there is no reason. But if all the engineering is done, the links figured out, coordinated, licensed, and equipment purchased and on the trucks, there is no reason that it couldnt be done in 2-3 weeks. Trenching in fiber is obviously another story.
(Edit: iPhone spelling)