I don't think it is. The novel I'm working on has 3 POVs, one of which is the bulk of it so far.

You can also change POV within chapters, as long as you denote it (the # in your ms, for example). CJ Cherryh does extensive POV switching in Hellburner, between *paragraphs.* (She can do it because she's awesome, but it was still damn confusing.)