The maximum you should take is about four grams in one dose, you wont do any real damage with that. Just dont take that much often, and certainly dont take that much if you have taken any APAP the days before or will after. The liver usually has enough glutathione stashed away to effectively clear the drug.
It is only when glutathione reserves are depleted by a huge dose of acetaminophen that the concentration of reactive metabolites becomes dangerously high. 4g is quite a lot, as the sudden spike in drug levels will put strain on the liver's antioxidant cache, but not a damaging amount. The liver needs time to replenish glutathione reserves, so you cant keep up doses like this for very long.