Gumshields are very important to use, even when not sparring , they help you to learn how to breathe out of your nose. This is important because if you don't know how to, you may open our mouth during sparring due to being breathless, this is a dangerous position to be in because a punch to your chin at this time could cause you to get knocked out. So next time you are training on the heavy bag or shadow boxing, keep the gumshield in, and bite on it at all times, try not to get into the habit of not biting it.