Having sat and frozen my nuts off in a Tin Triangle during a compass swing at Scampton years ago, I can assure you that it took 3 of us and no engines were running. Just the AAPP and an AEO to keep an eye on the electrical panel, a pilot (me) to guard the brakes and do the E2B readings - and a fussy old woman of a nav plotter ('Watt the Plot') to read the main beam compass values.
3 $odding hours of being towed behind a tractor it took us!