I can say from personal experience that backups are far more likely to happen regularly if your backup software runs without any manual intervention. And let me be quite clear: regular backups are the only kind that matter. I think it's fair to state this as a corollary to Murphy's Law: "The likelihood of suffering data loss increases in direct proportion to the elapsed time since your last backup." In other words, if you're performing all your backups manually, the one day you forget (or run out of time) will be the day something goes wrong.
In some situations, you don't have to do anything special to get backups to run automatically; in others, you have to be careful to set up your backup software to run at a set time.