Depends. When painting or getting the hands muddy in HydroCal, or laying plaster cloth, one has to stop and let things dry for a bit.
Working on engines or cars, I will work until I run out of parts. Or I fall of my stool by nodding off.
This past weekend I had 10 guys at the house building a layout for a nursing home. We took a break for lunch and totaled 77 man hours. I'll probably put in another 10 this week trying to put together the yard before all return next Saturday. It has to be done before we get too carried away laying track and switches.
I always have a plan and a point I wish to reach before hanging it up for the session. Sometimes I make it, sometimes I run into a glitch. But, when building the modules, I spend a couple of hours a day.....if I'm not fishing.
Another good thing about my situation is that the better half is my crafter and scenic person. We usually spend a couple of hours on the layout, when under construction, each evening after supper. And, yes, I help with the dishes. It is good bonding time and we both enjoy the work.
I really think she enjoys the trains more than I do. At least the building part.
Bob