[Arch-TK]

I don't carry around sources for well established industry wide facts which you can verify yourself by opening your eyes. Do you carry around a source that proves that using a keyboard to type is faster than using morse code?

James Hoffman (coffee professional, winner of WBC) discusses the obscurity of single dose baskets in his video here. He mentions they're not often used in the home because he is discussing home espresso but the 50 caveats of single dose baskets apply to the industry too.

https://youtu.be/3oFV88PzEFE?si=_cUs33SeovZ0jHYJ&t=549

Discussion of single baskets by The Wired Gourmet pointing out that in the industry double and triple baskets are used and split in vast preference to single shot baskets. Also covering the difficulty of working with single shot baskets:

https://www.youtube.com/watch?v=3OnH2Woluck

The Real Sprometheus video talking about single shot baskets, their obscurity,

https://www.youtube.com/watch?v=y0XariiJiHk

A cafe owner talking about why single shot baskets are not worth it in a commercial environment:

https://www.youtube.com/watch?v=-N3OlSa-4Wg

The reason people in this section are disagreeing with me is because they have never made specialty espresso and have no idea how difficult it is to dial in a single basket, even if you're a cafe.

[MichaelZuo]

And what of the second claim?

“All espresso based drinks” seems incredibly broad.

[Kirby64]

Again, this only takes basic experience in coffee/cafe drinks to understand this is true. The standard espresso based drinks are: espresso, cappuccino, latte, macchiato, cortado, flat white, americano, mocha, and a few other varieties. Every single one of those starts with a double shot of espresso (~1.5-2 fl oz of liquid). This is sometimes even referred to as a 'single shot' even though 1.5oz would put you in what is considered a double shot.

There may be some niche drinks that use less espresso liquid, but they're not common. If I was only given 0.8 fl oz (which, is what a single shot looks like) in an espresso drink I would be upset.

[Arch-TK]

Yeah it's a general rule, there are some exceptions, but they're less common than is worth challenging this claim for. Some drinks would be too strong to be made from a double, these will use a split single in countries where doubles are the norm. The second shot will end up wasted unless someone else is ordering the same exact drink or ordering a single espresso (also rare outside of Italy and some other countries). I've seen it but most customers prefer to see bigger drinks these days so most cafes don't usually face this problem and make drinks from double shots.

For reference, I use a 36g shot (basically 36ml if you wait for the crema to dissipate) for a 170ml "flat white" at home. This achieves a balanced strength for this kind of drink. You really have to get into the tiny drink category before you really reach the realm of "this is too strong and I must use a split single". And, in those cases, due to the fact of the double shot (and, I would struggle to come up with "sources" but it's again generally accepted that unless you can use the second split shot for a drink immediately, it goes down the sink), you are still often using a double worth of coffee for a single shot drink.