Once should be enough when it comes to shoveling snow out of your driveway. Unfortunately, snow can end up re-deposited across your driveway entrance when plows clear your street. The Missouri Department of Transportation has a simple solution to help you avoid a second round of shoveling.
Scooping snow about 10 feet away to the left of your driveway is the key. This leaves enough room for a snow plow clearing your street to deposit the excess snow in the free area you created, thus keeping your driveway entrance clear.

Watch this plow driver PURPOSELY cover up a car