[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.