I don’t know about others, but I know many Spanish colonies only worked 4-hours a day up to the 1890s. It could be tradition, and also unlike other Western powers at the time, Spain had not industrialised as much and would still have to rely much on physical labour. So I think the combination of Spain and its colonies being too hot to work for long periods, and lack of industrialisation, made 4 hour day work the way of life for them.