I've bought the same size footwear in everything for years and never had a problem, just Dunlop safety wellies are a size down. Then one day on a long walk wearing some cheap boots, my toes got hammered, toenails went black etc. So blamed the boots, and bought some Meindl dovre a half size up, best boots I've had, comfortable out the box, ideal. Until I did a long walk and I could feel my toes in the end of them
So bought some Altberg defenders a full size up for longer walks and had no bother, but obviously a cheaper boot. and that's my new size in everything, safety wellies up to my