yeah those were pretty common in the early days from what i understand=- I would imagine though that mice and rats and bugs and such woudl have no problems getting into the structures- They woudl be warm, soaking in the heat and retaining and radiating it back inwards for long period-
The ranch i stayed in was an old stagecoach stop/inn, and had no insulation, and when the wind blew- the curtains would nearly stand on end lol- so yup- they were quite drafty in the early days-