I've seriously attempted to quit intake of caffeine about 6-8 times over the last 2 decades. In each case, I was able to temporarily quit, with withdrawal symptoms being more in the 2-4 week range. However, in each case, a small amount of caffeine at a casual event lead to intake of "normal" (for me) amounts of caffeine immediately. I would love to quit it (as I understand it's health consequences).

As a reference, I would say that I would be in the "heavy users" category with a daily intake of about 750-1000mg.