Actually, 2 cans can be enough.
The caffeine amount alone is enough to fuck you over.
Most Monster cans are dangerously close to the limit. 2 is above.
People have just up and died after 2-4 cans after they stupidly went and done something active that pushed their heartbeat even higher, leading to failure.
It's also affected by your general health and diet as well, but it can still end even fit people.
And with the sugar on top, it makes things worse.
You have to remember it's not just the drink itself, but everything else that you consume on top.
2 energy drinks and a Starbucks is a common hospitalizer or killer.
I at most drink 1 can, but most days I actually only drink half a can. I put the other half in a small fruit juice bottle I keep for it. Works a charm because it's exactly half the can.
I usually get a 4 pack of Rockstar and it lasts 6-8 days depending on if I occasionally do a full can if I am doing lots in a day.