Not very often.
When I was at University, I used to buy one of those large bottles which I would sometimes use when pulling all nighters. I found that drinking too much coffee made you quite nauseous compared to energy drinks.
Also they would commonly be used as mixers on a night out. That's always a double edge sword though, as while it perks you up against the effects of the alcohol, you then up not being able to sleep when you get to bed.
They really aren't good for you, so now I would only ever reach for one when extremely tired, or hungover and need the alertness to do something.
Many years ago I had a job in a bar and there was a weird guy who used to come in on his own. He didn't drink, but always had Red Bull and would then go and dance on his own. One night we counted that he had a total of 13 cans, somebody then later found him in the corner, with serious jitters and convulsions.