354ml of coffee is quite a bit, even with strong robusta local coffee I don't do more than 180ml on average, and 4-5 shots sounds like a lot. I suppose if your body can take it, that's fine, but I do wonder if it'll taste like ass after an hour or so; won't it get cold?
I mean, it's just a lot of caffeine. I'm sure some people have no problem, but others will be off the walls or just sick. What's your typical caffeine intake? If you just want a hot drink to sip on for longer, try a couple shots of espresso and top the mug off with hot water for an Americano.
My regular morning brew is a 300ml moka pot in a mug with frothy milk. According to this I'm taking about 516mg of caffeine each morning, without spacing it out.
I have owned that thing for over a decade and have always treated it as a single serving device. I think FDA's wisdom is mostly a guideline, and nothing beats simply knowing your own tolerance.