There's a rather tiresome thread on a national romance writers' loop right now about "the rules." Not the rules pertaining to the loop--that one was two months ago--but the supposed rules of writing, like not using adverbs or "be" verbs and never switching point of view.
What it all pertains to is people wanting absolutes, paving stones in the yellow brick road, Arthur Murray dance steps, a golden template.
But, in reality, the process is all relative. "Be" isn't a "weak" verb unless it's overused. Adverbs ending in -ly are just fine unless they're every other word. (A note here: many writers who jowl on about this topic don't seem to realize many adverbs, such as "now" and "ever," don't end in -ly.) And the only problem with POV switches occurs when they aren't done well.
For heaven's sake, people. The name of the game is seducing a reader, page by page, chapter by chapter, book by book. Skillful storytelling is more important than "writing right."