Have you tried just making an Americano? Im a fan of strong coffee and thats what I do in the mornings.

Not a great idea, but not for the caffeine quantity that others mention (though perhaps for that, too). Espresso is meant to be drunk quickly and hot. Even the glasses are designed to keep the surface area minimal and give the drinker control over how (minimally) cool they allow the espresso to get.

Keeping a large amount in a mug for a while will allow bitter notes to develop and will mute the creamy and sweet notes/feel that make espresso worthwhile. You can minimize that a bit by diluting the coffee (a 3-hour old latte or americano changes less than a straight shot would in the same span), but it'll still change.

Pour over is really the only method that is intended to be drunk at varying levels of heat, and you can make it super strong if that's what you're looking for.

That's just way too much caffeine. My normal morning coffee is 10g of beans in a single shot.

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.

Sigh, stupid Imperial units.

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?

That's around what I do, either at home with my Aeropress or when I go to my favorite coffee place, a six shot iced espresso.

I only feel jittery if I drink too much at once, and almost never want more.

Of my at home mugs, sometimes I'll have a second but not always.

And I don't have any problems sleeping.

Don’t hurt yourself there!

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.