Whenever I use a new application I look up the frequently used menu options and the corresponding keyboard shortcuts, if any. It’s a lot faster than using the mouse for most actions.

Nowadays most applications are developed with the mouse as the primary or sole interface (look at some Electron based or similar apps), treating the keyboard as just an input mechanism for characters and numbers, and not supporting it as a navigation or control mechanism. I don’t see many recent developers trying to learn and use keyboard shortcuts either. They suffer through slow and imprecise mouse navigation and clicks.

Keyboard interfaces are faster for those who use it, but the OS and applications have to provide first class support. While I like macOS way more than Windows, don’t ever try giving up on the mouse or trackpad on a Mac. It’ll be mostly unusable and will waste a lot of your time in trying to get things done with just a keyboard. In Apple’s own apps, you just cannot do what you want to with the keyboard alone (Reminders has been a great example for many years — trying to navigate using tab or arrow keys would show how utterly broken it is).