The NCMAS didn’t have much to say about efficiency in our problematic, run-down, pre-WWII depot-level maintenance facilities (page 38) in those concentration areas. The report, discussed in another thread, also explains plenty of retention factors.We don't have the airframes to do that, plus there's a huge overhead in training systems and specialized facilities that would be impractical and costly to replicate. There are efficiencies to consolidating T/M/S in relatively few geographic locations.