"An important piece of evidence on the working day is that it was very unusual for servile laborers to be required to work a whole day for a lord. One day's work was considered half a day, and if a serf worked an entire day, this was counted as two "days-works." "
Presumably because in the other half of the day, they'd be working to harvest and grow their own food. I'm not sure what the difference is between working 8 hours, and getting enough money to buy food, and working 4 hours and then another 4 hours to make your own food.
First, if you are doing heavy work, like fixing roads, you usually can't do it all day. Neither can most draft animals. Second, the mid day meal was the big one, and there was usually a nap as well. People had to walk to work, and it would be hard to get everyone back at the same time.
Third, the Lord's inventory of tools was limited, so better to have two shifts of reasonably rested people than one double shift of exhausted people.
>> First, if you are doing heavy work, like fixing roads, you usually can't do it all day
Not sure if this is true. I worked at a building site labourer and I've seen people digging trenches all day. I'm also pretty sure in the poorer parts of the 3rd world people are toiling for 8 hours a day in manual/ox-assisted agricultural work.
Presumably because in the other half of the day, they'd be working to harvest and grow their own food. I'm not sure what the difference is between working 8 hours, and getting enough money to buy food, and working 4 hours and then another 4 hours to make your own food.