Crowding Cover means getting too close to an object and it can have major consequences for self-defense and competition. By crowding Cover (whether it’s a barricade, wall, barrel, etc.) you limit your options for target transition, reduce your speed, and in defensive situations increase the likelihood of your attacker being better able to cause you harm.
First, for target transition you need to properly use Cover to “slice the pie.” This technique allows you to stay behind Cover and then shoot the first target that comes into view, then the next, and next starting as you see them. If you hug in tight to your Cover object you have to lean out around it, so your body is exposed more with each target transition as you slice the pie. Staying a few feet back from the object will allow you to keep more of your body behind Cover.
Second, if you are crowding Cover you will have to take extra steps to move to either a new point of Cover, or to the opposite side of the object you are currently using. This typically requires one or two steps back then lateral movement. Crowding Cover can also affect reloads as you have to move back in order to gain enough space between yourself and the cover object in order to perform your reload without hindrance. If you maintain proper distance from Cover you will be able to quickly lean or step laterally in any direction you choose.
Finally, you want to present as little of yourself to the target as possible while remaining concealed from all remaining targets. If you crowd Cover you present more of yourself to the target being engaged as well as other targets, limit your field of view, and potentially expose yourself and/or firearm to any targets that may be hiding close to Cover. Stay several steps back so that you shield yourself from potential threats, respond quickly, and have freedom to move in any direction you need.