And mine wasn't directed at you, there have been posters who have linked it to pay/contribution.
If you clean at the weekend and maintain it on those two days, there's really no need to do any extra because you are off. When you work full-time, no one is messing up the house all day and so it stays more or less the same all week. At the weekend, if there are two of you, one can mind the kids while the other does x or y job. It is much faster to do larger chores without a kid in tow.
As for what people do all day if not housework, well, it's not really hard to actually spend your time doing other things.
We get up, have breakfast, get dressed, go out to the library, to a playgroup or to the supermarket, come home have lunch, tidy up after this, ds has naptime/I work, he wakes up, we read a few books/do a few jigsaws/play, tidy up after this, go out to the playground or for a walk or to a friends, come home, make dinner. Could I do more housework? Yes, but it would be inefficient, taking 2-3 times as long as doing it on my own, would probably involve me getting frustrated with ds for increasing the work by enabling the kids to mess things up behind me as I tried to do it. I spend a lot of time focused on getting ds to do chores and tidy up after himself vs just tidying for him, which makes tidying up after play much more drawn-out than if I just got it done quickly.. e.g. if I sweep, he sweeps with me, but usually that means he bats his toy brush about in the dust and I have to sweep it again, but that's why I'm here. Not to keep the place spotless, mow the lawn etc. If there is something obvious that needs to be done and there is time on a rainy day, of course I'll do it. But not because I am "expected" to, or I "should" because I contribute less etc.