6ft hovering drones? Hovered over a town all night? These are unusual drones. You have to put engineering effort in to keep a drone up for more than 30 minutes and 6ft is really big for a hovering drone.
Other aspects to consider are that the “drones” are replaced by others as batteries deplete or that the drones aren’t really there as long as people believe.
It’s possible that someone is doing this as a hobby for artistic, conspiracy theory “reconnaissance“ or benign data gathering-purposes or conducting some sort of investigation or intelligence gathering.