1.) It's important because it helps to ensure that the reader gets the best and most informative experience from the writing. Articles that haven't been mastered tend to come off as choppy and unprofessional.
2.) Keep reminders EVERYWHERE. And listen to your body, especially when you start to feel tired. When you're tired you don't give 100% to your task, so it may be better to step back for a few minutes before coming back with new eyes.