Well, I developed a caffeine hyper sensitivity back in the naughties, so I only drink decaf now, and only one when I do, which isn't every day.

However, back when I was drinking leaded, I would usually have one cup once I was up for whatever day-equivalent period I was in (I tended to work evenings and/or nights), and supplement caffeine hits as needed via coffee, so most days it was two or three cups, and I'd stop about four hours before bedtime.

Sometimes, when shit was crazy, or when I was doing a DM session, I'd drink a pot or two a day. My ttrpg groups tended to coffee as blood, so it wasn't unusual for three or four of us to end up making a pot, finishing it off in one run, then start the next one. By the time the cups got cold, we'd be ready for the next anyway.

I can remember one weekend where I was working two jobs, and managing one of my side gigs as a writer of custom fiction. I literally had a cup in my hand for most of twenty hours a day, and it never got cold. Left my main job at 10 on a Friday, drove across town to the club I bounced at the most, drinking an iced coffee the entire way. Did my shift there, with an insulated mug that one of the bartenders kept refilling for me (and I normally hate black coffee unless it's fancy shit). I got off at 3, drove home and crack open the laptop and mainline lifer's juice until I couldn't go any more.

About 7 or 8, I twitched my way into bed, my skin crawling and my ears buzzing. Slept until around noon, got up and did my workout while alternating between coffee and water.

Finished that, and took a shower, got ready for my first shift on the door at a smaller bar and fucked around editing until 5, slowly drinking creamy hot goodness. Then off to the bar, with a different barkeep maintaining my supply until 10 and time to go to the club. Repeated that Sunday too.

I have no clue how much I actually drank. The insulated mug I had was a 16oz one, and it never got empty, but it would get low every fifteen to thirty minutes.

But that Monday morning, when I got home and settled in to try and unwind, about the only thing I did was poop a lot and vibrate. Took me until maybe two hours before going on to my first patient to get to sleep.