|This is an issue when you make your backups with labels. The labelled tapes are called a "managed" backup set by MS.|
I've found it a whole lot easier to go without the labels and do an "unamanaged" backup set.
Then the backup doesn't care what tape is in the drive, it just performs the backup. This means, in the case of a long weekend for example, you don't miss a backup. However, your Friday night backup would be overwritten by the Monday night backup, but in my books, that was always fine by me.
The following hard to find document explains how to properly setup backups in Windows. It shows both methods, but as I said, I preferred to go with an "unmanaged" backup.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.