Lol. I've taken caffeine too far as an ultramarathoner and let me tell you it isn't pleasant.
Caffeine is massively helpful as an ultramarathoner since it blocks the systemic fatigue response and improves muscle endurance. The tendency is to limit test to see how far you can take it. My limit was 400mg every four hours via pill plus 50mg every hour via energy bar. Doing that over a 24hr period is way, way too much caffeine, but I felt like I could handle it. It became my routine.
On one occasion I tried upping my pill does to 600mg every four hours. I ended up ODed, with irregular heartbeat and light headedness, 30km from the nearest road. It was unfun, to say the least.
My cautionary tale is an extreme one, obviously. Nonetheless, the message is generalizable. Caffeine is ubiquitous in our society, but it is still a powerful substance that needs to be handled with caution and respect. There is such a thing as too much.
It's hard to OD with coffee but you can still mess up your sleep. The bedeviling thing is that caffeine users often don't make the connection between their substance use and sleep disruption, even when it would be obvious to an outsider. IMO, the best practice for a coffee drinker is to keep track of your dosing, both amount and time, while also maintaining a sleep journal. It's easier to notice patterns when they're on paper.
That said, I agree with Captain Janeway: