How much you should take depends partly on how much meat you eat. The avid carnivores probably don't need to take any, and vegetarians a lot (?10-15gm/day?). I take 5.
I think it depends a lot of your goals. Nobody really needs to supplement creatine. It's just used to many purposes and goals. Maybe if you are a vegan athlete, it could be recommended. But otherwise creatine is just there to improve your performance and sometimes to burn fat. All the positive effects around that are just bonus. Meat doesn't have that much creatine when you really get down with the numbers. You'd have to eat over 1kg (2.2lbs.) of meat every day to get to the 4-7g per day recommendation. 10-20g I think is more suitable for a loading period if one is planning to do that. Most reasearches use the 3-7g daily doses with good results and no specific loading phase, so I like to stick there as well. Of course one can always test and try different amounts and see where that goes.