I’d like to clarify something that, although nit-picky, is pretty important in my opinion. Instead of claiming that personas should “guide every element of the design cycle”, I believe it’s more accurate to say that they “inform” design. The difference is in seeing personas as the ultimate authority or as a magic bullet vs. another tool in our toolbox. The latter description is more realistic.

Personas won’t give us all the answers. They do provide some answers, for sure. But they also inspire us and help to inform our intuition as designers.