The people who say they need 3 cups of black coffee to start their day are just addicts with a high tolerance that experience mild withdrawal symptoms each morning.
If you feel like that, it’s your body crying for you to take a break.
If you like an occasional cup of coffee or energy drink to get through something, then that’s fine. But if you ever feel like one isn’t working like it used to, you should take a break from caffeine to reset your tolerance, not up the dosage like an addict.
Possibly, and the effect definitely decreases over time (so far, anyway). Could wish it would decrease enough that unexpected caffeine content didn’t set it off as hard, like espresso powder in brownies lol.
And it is dose dependent, along with being fairly easy to detect the first signs of it. Means it’s only the hidden doses that get me now. I don’t mind decaf at all since the market for it has reached some decent brands and even regionals like blue mountain can be had.