How often you backup your files should be determined by how often the files are changing, the type fo internet connection and the speed of your internet connection.  If you're trying to backup your music library and you're not adding any new music to it, you may want to only back that up once per week.  If you're backing up your server with client data on it that's being modified on a daily basis you may want to synchronize those files more often.

How often you backup should also be determined by the type and speed of your internet connection.  If you are on a broadband connection at home that is always on or at the office with a constant internet connection you may want to choose to synchronize your files more often.  If you are on a dial-up connection, you may want to only choose the manual method of synchronizing your files since an internet connection is required.

The time of day that you choose to synchronize your files is also important.  Althought there is a way to set a speed limit for the synchronization process you may want to choose a time to synchronize with the server when you expect the least amount of network usage.  This is especially important in an office environment that might not have an incredibly fast internet connection.  Be courteous to your fellow network users because the BackupSpace.com Agent will use all the network bandwidth that's available which can cause other internet applications to appear to run slowly.