I can see how PT work can be a problem. I work a 5 day fortnight and it is shift work. On days that I work arvo shifts it is not unusual to only have a couple of hours sleep before spending the day looking after DD. I love that I still get to have a lot of time with her, but some days I'm so tired I can barely face the thought of cooking dinner, let alone all the other house work.
Peoples expectations of a PT worker are different to a FT worker. I find that I'm still expected to do all the social things and people are less understanding of my tiredness than they are of my FT friends.
But despite the tiredness I don't think I'd change things. I get reasonabley well paid and get to enjoy the company of other adults. If I have to spend a couple of days being tired so I can enjoy being with DD and not have to worry about finances then I can accept it.