Backing up multiple servers using one tape drive

Recently upgraded to 2012 from 12.5. I have 4 servers backing up to an LTO3 tape drive. Approximately 250G data, which took around 7 hours using 12.5 and doing full backups each night.  

I am using the TECH189306 article about setting up mutiple servers to back up to one drive. I have one question; I have set the append time to 12 hours for the backup set, what should the overwrite protection be set at? It's set to 1 hour now. 

Thanks