(Just to clarify, I don’t pretend to follow all my own rules! I’m still learning to do that…)
‘Head-hopping’ is the name many writers give to the act of switching between different characters. I like to think of it visually as moving the fictional camera from behind one character’s eyes to behind another’s. This crops up a lot in collaborations, which isn’t so bad, because they’re good practice, but rarely go much further, and in third person omniscient, which I find a lot in the traditional classics. In many cases the character’s thoughts are included in the perspective (a POV can be in first or third person–or second, indeed).
As a reader, I feel spoon-fed when I know the exact thoughts of every character. I like to contrive my own elucidations of supporting characters–it builds so much tension! Actually, my favourite characters in books are rarely the protagonists. There’s always one supporting character whom I love to be surprised by, or who I imagine I can relate to.
As a writer, it takes a good deal of deliberation to create a unique style of thought for each character. It’s a bit of a trap, really–we have so much to tell our readers, and everything we have to tell is dreadfully interesting. But we also profess to appeal to an audience of young people just as intelligent as we are, and who can draw generally accurate conclusions from the smallest details.
‘Less is more’…‘quality not quantity’… I used to despise these sayings. I wanted to write at length. I wanted to write everything in my mind and more besides, going off on a tangent at every turn. But writing is a deeply rational process, and it’s rare I’ve seen writers make head-hopping work.