Don't worry: your tolerance will eventually reach a level such that you would have to consume physically impossible amounts of coffee for it to have any effect.
Personally I find that there's a dynamic balance that forms. Any less caffeine and I'm a zombie, any more and it just feels physically repulsive. You make a cup take a sip and your mind is like Just No.
For me that balance is at about 400 to 500 mg of caffeine per day. Stays stable for months and months, then I tend to reset a bit during a vacation of or 3-day weekend of some sort.
Don't need caffeine at all if I'm not mentally working. Barrly crosses my mind.
