sebra/Shutterstock It has probably happened to you before, or at least someone you know. You lose your phone , it's stolen, or it goes kaput. With it goes all your precious photos, videos, and other important content. This is an easily avoidable issue by keeping your phone backed up on your computer or a separate drive. Some also work with companion services like Apple's iCloud or Google Cloud.  While you know how important it is to back up your phone, you might wonder how often you should do it. While there's no specific right or wrong answer, most experts agree that you should do so at least weekly, depending on how much new data is added to your device. For casual users, weekly or biweekly might suffice. You can get away with monthly if you don't often save much new data to the device.…