There are no "rules" to how long you live with your parents, and anyone who says otherwise is a moron. There are very few people in this world who will be prepared to give much of a **** about you besides your family and blood, and if a person needs help with their living situation for longer than is "average", for whatever reason, then as long as both they and more importantly their parents are cool with it then who is anyone else to judge. Yes, it's not going to look attractive to many women if you are still living with your parents at 30+, but better to have a good standard of living then be in a rathole that you can barely afford. 

However, as a young adult (which I still feel I am), I think it's healthier and more interesting to live in your own home by your own means. For a lot of people it's a learning curve as to how to budget/deal with money, utilities etc... I don't turn my nose up at people who still live at home, but it's just personally something that I'm glad I did for a while, but happy to have moved away from.
