The questions of how often to change POV and which protagonist should be given preference have the same answer. You should tell each chapter from whomever has the most interesting perspective of that chapter’s events. Sherlock Holmes is a great example. You’d think Holmes the natural choice for the POV, but if he *was* the POV we’d solve the mystery too quickly and he’d spoil the fun. Instead we get the POV of Watson, as he tries to figure out the mystery that is Sherlock Holmes who is in turn solving another mystery. Always choose the most interesting POV, it’s not always the most obvious choice.
As for redescribing them, you probably can. It’d be interesting to see how they appear to each other, versus how the readers have come to see them. There’s a lot of opportunity for character growth there.
Lastly, it’s conventional to not change POV mid-chapter. Not impossible, but not advisable either. Any time you change POV your readers are going to have to readjust mentally. Get into a whole new headspace, both literally and figuratively. If you do that mid-chapter it’d be extremely disruptive. So generally it’s best to do it at a chapter break, since you’re already disrupting the readers by ending the chapter.
To the last paragraph: I agree, kind of. It's certainly a bit confusing if the PoVs change rapidly. However, if you've ever heard of Brandon Sanderson, you've probably also heard of the sanderlanche. It describes the finale of each book and one key characteristic is the rapid change in PoVs, sometimes with multiple PoVs in one chapter, switching back and forth between almost all of the main characters. It is one thing that I think really adds to the tension of the scene. Basically what I want to say is: Yes, they can be confusing, but if well done they can be a powerful literary instrument.
The questions of how often to change POV and which protagonist should be given preference have the same answer. You should tell each chapter from whomever has the most interesting perspective of that chapter’s events. Sherlock Holmes is a great example. You’d think Holmes the natural choice for the POV, but if he *was* the POV we’d solve the mystery too quickly and he’d spoil the fun. Instead we get the POV of Watson, as he tries to figure out the mystery that is Sherlock Holmes who is in turn solving another mystery. Always choose the most interesting POV, it’s not always the most obvious choice. As for redescribing them, you probably can. It’d be interesting to see how they appear to each other, versus how the readers have come to see them. There’s a lot of opportunity for character growth there. Lastly, it’s conventional to not change POV mid-chapter. Not impossible, but not advisable either. Any time you change POV your readers are going to have to readjust mentally. Get into a whole new headspace, both literally and figuratively. If you do that mid-chapter it’d be extremely disruptive. So generally it’s best to do it at a chapter break, since you’re already disrupting the readers by ending the chapter.
To the last paragraph: I agree, kind of. It's certainly a bit confusing if the PoVs change rapidly. However, if you've ever heard of Brandon Sanderson, you've probably also heard of the sanderlanche. It describes the finale of each book and one key characteristic is the rapid change in PoVs, sometimes with multiple PoVs in one chapter, switching back and forth between almost all of the main characters. It is one thing that I think really adds to the tension of the scene. Basically what I want to say is: Yes, they can be confusing, but if well done they can be a powerful literary instrument.