Hello,
That is a question which frequently comes up from members of the forum, but the answer can vary greatly based on the amount of data, reliability and cost of backup medium, time window for doing backups and so forth.
You can view some of the messages threads about backups
here,
here,
here,
here,
here,
here,
here,
here,
here,
here,
here,
here and
here to show a few of the many discussions.
As you can see, there are many different methodologies for backing up one's computer(s).
Regards,
Aryeh Goretsky