If this is a commercial system, or any other with vital information on - the professional way is to maintain three generations of backups.
Preferably the backups should be on removable media (external hard drive possibly), each should be on separate media - and should be kept in a secure place away from the system (in case of fire, theft, etc.
In such a case the last thing you should do is lessen the frequency of backups.
Not having a backup is very unwise - even if you don't think you have anything important on your machine.
Do you, or will you, enjoy re-installing your computer system by hand (over a period of several hours/days) to get something resembling your computer as it is now? Or would you prefer to get it up and going again, exactly as it was, in about 20 - 30 minutes by using a backup?