It's all about each table's atmosphere. I'll leave a table after 4 hands if I notice some crazy players, someone getting way too lucky, or an extreme LAG.
Cash tables are all about getting out once you hit a profit, the only reason to stay at a table once you've doubled up, is that there's a rich fish still sitting there. Always leave, unless there's a really strong chance you will win more. Although, even if there is, you're almost always better leaving.
Reset, get new tables, or go back to work/study.