The problem is, essentially the only thing anyone agrees on when it comes to "how much" is "its different for everyone". So what's not different for everyone?

The problem is, essentially the only thing anyone agrees on when it comes to "how much" is "its different for everyone". So what's not different for everyone? Well, if your pee is dark, then you're probably dehydrated. Ok; now we have a useful signal. It's not perfect. It doesn't capture the subtleties of the entire situation. But it's USEFUL.