When I started to write novel length fiction, I was as ignorant of the lexicon and rules of writing as my dog is of particle physics. Well, I can't speak for my dog. She is pretty smart and seems able to open secret doors to an alternate universe full of tennis balls. . .
But I digress. . .
I didn't even know what POV stood for, much less what to do with the darned thing. My critiquers kept indicating "POV violation" in the margins and it took me a little time before I had the courage to ask what the heck that was.
Now I see issues of POV inconsistency everywhere. In TV shows, in movies, in books. (My inlaws rented Kevin Spacey's "The Usual Suspects" and I got a whole room furious with me when I figured out the plot twist mid-movie and showed them where the POV violation was that gave it away.)
I guard against POV violation in my own writing as well as play with POV for effect. I've now written in 'wide' 3rd person (with many POV characters--closer to omnicient, but still definitely through the character's perceptions), 'close' 3rd person (limited numbers of POV, tightly focused on the character's perceptions) and single narrator 1st person POV. Each has advantages and disadvantages. These are some of my experiences and opinions regarding the different points of view.
The 'wide' 3rd allows for a story with a sweeping scope and side plots. It allows the author to show facets of a character through the eyes of another character. Subplots don't rely on a particular character having to be 'front and center' all the time. On the down side, it does tend to splinter a story and can break continuity and tension, especially when the story leaves one set of characters to follow another. The writer has to avoid the kinds of 'meanwhile, back at the ranch' transitions that feel manufactured and awkward. "Wings of Winter" is written in wide 3rd and it seems just right for the epic feel of that novel.
Narrow 3rd allows the author to get much closer to the character. Almost as intimate as in 1st person, but without the limitation of the story seeming tunnel-visioned. A tight character focus with a limited number of POV characters can keep tension high and the story unified. "MindBlind" is written in narrow 3rd and it keeps the thriller aspect of the book fresh while allowing for a complex plot with a group of characters evolving through the story. There is still the issue of needing to transition between segments of the story.
Single 1st person can keep the story focused and highly unified. There are no adjunct characters running off with the plot and the main character stays in the heat of the action all the time. This can present difficulties in fully fleshing out the other characters as well as showing necessary subplots. "The House of Many Doors" is a 1st person project and I had to work hard to show the second protagonist's personality through the POV character's eyes. On the plus side, it kept the story tension quite high and the plot unfolds for the reader as story events unfold for the POV character.
My current work in progress ("WIP"), "Heal Thyself" has ground to a halt at a little over 10K. I have plenty of outline left to write to (I only outline a few chapters ahead) but I don't know if expanding the number of POV characters is right for this story. Right now I'm writing in narrow 3rd with 2 POV characters. I think I need to expand, but I don't have a solid sense of this (important) secondary character. I'm trying to get to know Kayla Baen. Perhaps a game of 20 questions will be helpful. Or highlighting several anecdotes from her past--details that will never be written into the novel, but give me a taste of who she is.
My sense is that this project will remain in 3rd, but with several secondary POV characters in addition to the 2 main POV characters. This is a story with sweep and scope, more epic than thriller. Yet, I don't want to widen the field of view too much. I don't think the story will work well in that case.
Happy writing and remember to show your poetic license if you get pulled over for a POV violation.