The Most Common Positioning Mistake That I See Companies Make

I think the most common positioning mistake that I see companies make is they kind of just don't position deliberately. So maybe could you give an example about, with some of the companies that you've either been at or worked with, how to bring this to life? Like what's an example of a company that just got positioning totally wrong? And their mind of like what they think they are and then what they actually are, and where they fell down.