I love the UX-design book: Don't Make Me Think.

There's an idea in this book, that when using a mouse, smaller buttons are harder to click because you need to stop the cursor inside its hitbox, but moving the cursor to the edge of the screen is easy because it's effectively a huge button whose height is infinite (or infinite width for lateral edges). And hitting a corner is even easier because it effectively has both infinite width and height!

This means that if there is an actual, finite button on a corner, the easiest way to click it is to position the cursor on the very corner, rather than attempting to position the cursor in the middle. But this is ruined if this button has padding. So for example, the start button on windows at the bottom left corner had padding in earlier versions of windows like windows 98, but the actual hitbox of the button shouldn't have padding, so that it's easier to click.

This is all to say that I use Firefox maximized, without a titlebar or menubar, so that the "back" button is at the top left corner of the screen, and the hamburguer button is at the top right corner. But those buttons have padding! If I actually move the mouse to the very corner before clicking, I miss the button

That shit is infuriating

Steve Krug's other book, Rocket Surgery Made Easy, got me into usability tests with real users, and how to get it in place in a corporate environment. It's shocking to watch real users use software.