As with writer’s block, what works for one person may not work for another. But here’s some spaghetti to throw at the refrigerator door:
The answer is, it depends. If your manuscript is absolutely riddled with errors, then publishers and literary agents who skim your sample chapters might find it so distracting that they write you off without much consideration.
Most books benefit from research–but how much is too much?
If you’re an author or screenwriter and you’ve never watched the YouTube series “Everything Wrong with…” by CinemaSins, then I have homework for you.