An interesting exploration of Tesla’s recent update to their in-car control screen that resulted from the author not being able to find the defogger control. Here’s an example of the kind of analysis he provides:

Edward Tufte has this visual rule that 1+1=3. With a single line on the screen, you have just that single object, but adding a second line does something interesting, it adds a third ‘object’ on the screen, the negative space between the two. All good visual designers deeply understand this effect.

In UX design we have a cognitive equivalent. If you have two buttons, there is a third ‘object’ created, the decision a user must make on which button to tap. This cognitive load is invisible and rarely discussed but it can be a real source of confusion.