I drink on average 10-16 ounces of super concentrated cold brew espresso every day. I really should get the caffiene content measured on this stuff.... it is ridiculous though. I have been told that one sip of my brew is enough to temporarily cure a pretty mean hangover. There is no life before coffee.
Several years back, I can drink up to 4 tall size commercial coffee from starbucks or other coffee shops. That was my way of life until I suffered from GERD which I was force to limit it to 4 cups in a week. But, it's really very hard for me so I tend to drink 1 cup daily of my own brewed beans.