That's when I realized POV isn't a matter of style or voice. The story dictates how it wants to be told.
I love how the "rules" on first/third person are changing. I've seen novels with the protagonist in first person and the other POV characters in third person. What truly matters is a well-written story that's mesmerizing.
The best story is intimate
Deep POV can be as nearly intimate as first person. That's because deep POV means more than simply showing the scene from that character's perspective. It means staying completely true to his/her view of everything. You can't slip and tell something the character can't possibly know.
Nor can you write a scene in a manner untrue to the POV character's personality or backstory.
What does that mean? It means not showing other characters as they truly are, but only as the POV character thinks they are. If your protagonist, we'll call her Nancy, had a run-in with a bully in the 1st grade, and this bully was a brown-eyed blonde named Julie, then Nancy is going to have a natural aversion to any brown-eyed blonde named Julie. Instant conflict, especially if your character Julie is a sweet woman who only wants to be friends.
It also means staying true to only what the POV character's knowledge. Whether you're writing historical or contemporary, resist imparting any information the character wouldn't or couldn't possibly know. In historical writing, that would also mean the words they used.
One of my critique partners used a word I thought was too modern for her character. I looked it up in the etymology dictionary and discovered the word had its origin about 10 years prior to the story. BUT ... did that mean the character would know it? This was 1838. No Internet or Google. However, the character's father was an educator, so I realized she could very well have known the word. I didn't suggest a change.
One of the best books I've ever read for staying true to the character's knowledge is Jessica Dotta's Born of Persuasion. Written in first person, Dotta stays true to her protagonist's worldview. She never tells the reader anything the protagonist doesn't know, so through much of the novel, the reader isn't always sure who some of the characters really are.
There's mystery attached, simply by resisting the urge to let the reader know what's really happening. It brings your reader totally inside the POV character's head, allowing the reader to experience the novel, not merely read it.
And isn't that the goal? Hey, nobody ever said writing a novel is easy. Being an author ain't for wimps.