Earlier quoted context omitted.
The timing can also play into it (not sure if by 'plan' you mean down to the hour as well). https://i.imgur.com/1IyKjSg.jpg As I get older, my tolerance has lowered. I used to be able to handle a Starbucks 'tall' cup, but now I can only drink two espressos at most, if spaced out by two hours or so. If I go over my limit, it's 7-9 hours of lying still in a dark room with a migraine-like headache. For more on cortisol…
Starbucks drip coffee contains a lot more caffeine per serving than espresso... I have seen figures that a venti size medium roast can be 280mg total, while single espresso shots might be as little as 70mg. https://www.kickinghorsecoffee.com/en/blog/caffeine-myths-es...
https://globalassets.starbucks.com/assets/94fbcc2ab1e2435985...
Recommended daily caffeine limit is usually quoted at around 400mg for an adult, although there's not a lot to back that number up.