Point-of-View is one of those funny things writers get very worked up about. And I’ve noticed, reading through some older books I have, making concrete POV choices is a relatively recent development. I mean, yes, certainly, the distinction between first-person and third-person (and the rare second-person) was always clear. But third-person was often more of a muddled third-person-omniscient instead of the discrete multi-person third-person-limited, where individual scenes have a clear POV character. Even the idea of a “POV Violation” as a writing mistake seems to be a relatively new thing.
Because, let me tell you, a lot of classics are just loaded with POV Violations.
However, the standard today, when writing third-person multiple-POV is for clear, discrete definition of whose head your in for any given scene or chapter. George R. R. Martin’s Song of Fire and Ice books do this explicitly, telling you who the POV character is instead of a chapter title. I hear a lot of “rules” of how to do a POV character, who can be one in your book and when you can let them be one. I’m of the opinion that who can be one and when is whoever you need it to be for the scene, whenever you need that scene to be. Frankly, one of my favorite bits in The Holver Alley Crew is when Mila steals the dress from the rich woman, because it's from the woman's POV. She's just a one-off character, that scene alone, and some people will tell you it's against the "rules", but I say BAH.
My big thing with POV is trust. Unless the Unreliable Narrator is a technique you’re utilizing, then you have to present your POV character in an honest way. You have to have trust in that character and their engagement in the plot.
Now, that doesn’t mean the POV is limited to the “good guys”. I love my antagonist POVs, as long as they are antagonists that I can trust are being honest with how they engage in the plot. If I have a character who is against the hero privately, but acts as his friend, and I don’t want the reader to know that… then that character can’t be a POV character. But if I want that betrayal clear, then that’s exactly who I want as POV.
This was especially hard for me in A Murder of Mages, which is probably my most constrained work, POV-wise, in that I only have Satrine and Minox as POV characters. This is because, at its core, it’s a murder mystery, and if you go into the head of murderer, then the mystery is given up. By limiting the POV to my two Inspectors, then the reader has the same set of data that they do.
In The Way of the Shield, it’s more complicated than that, but similar rules of not using a character for POV apply. There are people whose motivation and trustworthiness I want the reader to keep in question, even in a subconscious way. Ideally, when their truths come to light, it will hit the reader like a hammer, because they might not have even suspected it. That's where a lot of the fun is.
Right now, I'm working on The Fenmere Job, and I've imposed one rule regarding POV on myself for it, because I think it's the best choice for the story. But I might decide over the course of things to break that. If that's what's best. We'll see.