What did you use to measure those 6" boards in the bedroom??lolololololo just say Peter length lolololoWe have a good number of houses with floors like that out here. Usually old farmhouses. Most common, like my house is 1-1/2 wide.
Back in the day poor people would buy the wide boards because they were cheaper. It takes more time and expense to produce the smaller boards. Kinda a status symbol.
My house was built in 1900 and added onto at least twice. The flooring is a mix. Downstairs are the 1-1/2 boards for entertaining, the bedrooms are all 6” wide.