There is a lot to be said for living on your own before marriage and being independent. I agree everyone is different, but I know people who got married very young, and it can be hard, if say a spouse passes away or they get divorced later on. To each their own, but it is something to think about.
We don’t have set chores, but we expect anyone living in the house to help out. If mom is making dinner, help set the table and do the dishes. Don’t leave a mess in the bathroom. If something needs doing, do it. If Dad asks for help cleaning the rain gutters and you’re just sitting on the couch, get up and help him. If mom asks if you can please mow the lawn, do it. It would be the same if I asked my H if he could take out the garbage or clean the counter…you live in the house, help out.
I think as long as everyone is fine with it, there is no issue with an adult child moving home. I do think it’s a problem if they move home and do nothing but sit on the couch all day. I also don’t think it should be permanent. If a kid is working full time and wants to move home for a little while to build up the savings and they help out with chores and even pays rent to their parents if needed, that is fine.