Basic day job
The general job market construct of the hours in which some people do work. Start at 9 am and at 5 pm.
Some times referred to as 'Bankers Hours'. Since the Agricultural society
was more geared to "getting up with the chickens"
to milk cows, plow the fields and do chores
till the son set with occasional breaks for lunch, supper and a dip in the river to cool off. With the ushering in of the industrial revolution
, work hours became more set and the average office job
became a 9 to 5. Manufacturers set work hours in shifts 8am-4pm day shift 4pm-12mid afternoon shift 12mid-8a overnights.
Now with the information age and the internet the demise of 9 to 5 seems inevitable. Although it may continue to exist. Bankers no longer have to be consulted, much of business can be conducted online. People can work at whatever time of the day they like.