How intelligent are incremental backups in Windows Server Backup

[CyBeRkId2002]

I am looking at implementing Windows Server Backups in one of the primary schools we support where cloud backups are just not going to be cost effective.

 

My plan is to use Windows Backup and rotate around 3 x 3tb HDD's (1 in use, 1 stored within the school in a fireproof safe and 1 termly drive stored off-site at a second college).

 

My question is if using incremental backups how well does the system deal with versioning? Obviously we do not want to backup to multiple drives that are dependent upon each other. If one fails / goes missing we still want to be able to recover from another. I am presuming Windows backup is intelligent enough to put a master on each HDD, and put delta changes relevant to that drive?