When they worked, it was from dawn to dusk doing hard labour.

Read Witold Rybczynksi's Home when he talks about medieval life, pages 24 - 36 in my copy.

And if the harvest wasn’t good, they died because the Lord took his tithe regardless.

That's how feudalism worked.

And that’s not to mention the household labour, all of which we take for granted (consider chopping wood every time you wanted heat, mending clothes or the ridiculous process of cleaning them.)

These are pretty self evident. Unless you think they had chainsaws and washing machines in the dark ages?

The only stuff that’s counted in that 150 days silliness is working the land which was only a portion of their real labour.

This is linked in the source I already provided, you can look at the original study: https://groups.csail.mit.edu/mac/users/rauch/worktime/hours_workweek.html