That never was the case (except for short periods after salary increases).

And this is not a question where there could be any speculation: in those days there were already people collecting such statistics, and we have a bunch of diaries describing the actual state of affairs, both from the workers themselves and from those who organized their labor - and everything shows that few people worked more than 50 hours a week on average.

Most likely, the myth about 80 hours a week stems from the fact that such weeks really were common, but it was work in the format of "work a week or two or a month for 80 hours, then a week or two or a month you don't work, spend money, arrange your life"

There is also agriculture, which employed a significant part of the population in the past. There, on average, there was usually even less than 40 hours of productive work, it's just that timing is of great importance there, and there are bottlenecks, and when necessary, you have to work 20 hours a day, which is compensated by periods when the workload is much less than 6 hours a day.