More rules, you say. Yes, and they are probably also wrong. What is true is that editors like to find excuses to reject, and it's better not to give them any. On the other hand, they aren't always right.
Great comment, Bob. In fact, the whole discussion is fascinating. It's given me an excuse to procrastinate and avoid my own writing for over a quarter hour now! But now it's time to confront my demons and "git 'er done," as Larry the Cable Guy would say.
Blindly practicing can be detrimental though. You can go to the golf course and hit balls, but what if your posture and club handling is all wrong? You can learn bad habits that are hard to unlearn. That's why structure and focus are important to make sure you practice is efficient and not just a waste of time.
That's why writers are encouraged to join critique and reading groups. They will be able to tell you if your literary "posture" is wrong. I definitely encourage critique groups and such. I am just against giving money to people who claim to have the secret to getting published.