Character Internalization: To Italicize or Not to Italicize?

Here's the latest from Jami Gold, Paranormal Author :

A few years ago, Marcy Kennedy guest posted here to share three writing problems we can solve by understanding internal dialogue. At the time, I gushed about her book on the topic, Internal Dialogue (Busy Writers Guides Book 7), and that book is still the best resource I know of for really understanding how to make our characters thoughts work for our story.

As Marcy says in her book, internal monologue (also known as...