There’s a very good reason that the law applies a “cooling off period” to so many things. There’s definitely a cooling off period that should be implemented by new writers, and that’s taking a moment to count to 10 before you rush out and make all kinds of crazy changes to your novel.
A word to the wise: the minute you publish a novel, every person you know suddenly becomes an expert. I even had someone tell me my book needed a different model for the cover. She proceeded to show me a photograph of someone who was downright scary looking. No offense to the Joanna Lindsays or Rosemary Rogers of the world, but my novel is not a “sex book.” Rather, it’s historical fiction Victoria Holt and Belva Plain style: heavy on plot and character development and light on sex scenes. So, when this well-meaning friend showed me a Fabio-type male model in a leather vest as opposed to a wealthy Englishman in era-appropriate attire, I simply had to smile and decline.
People are always well-meaning with this type of unsolicited advice, but overall, it isn’t helpful. That’s usually because there’s a lot they don’t understand. (Like using a book cover that doesn’t fit the book’s genre.) If someone is bringing up confusing dialogue, plot holes, typos, or similar issues, listen and listen well!
However, those who are simply offering to rewrite your novel for you (or redesign its cover) should be, well, politely ignored. I’m not saying you should hurt their feelings or act like their opinions don’t count, because there’s no need to create ill will. Just don’t get carried away and begin second-guessing everything you did merely because of so-and-so's “expert” opinion. Be polite, be nice, smile and nod, but never make changes to your book because of someone else’s personal opinion. Write on!