The grandfather - father - son schedule is the most widely used method, and involves backing up data in following way:

This system is far more powerful than the five tape rotation, but requires more tapes.

For example, consider the calendar below:

This strategy provides you with the ability to restore data from the last week, plus any Monday over the last month, plus any month for as many monthly tapes as you have. Variations on this scheme are available, and provide a trade-off between the number of tapes required, and the number of monthly tapes available.