Incremental scans are faster, but with time they become less accurate.
Therefore, after a number of incremental scans it is recommended to perform a full scan.
Here you can schedule periodic full scans to be executed after a certain number of incremental scans.

Alternatively, if you want to run full scans on weekends, you can create 2 separate jobs.
First job - to run incremental scans on weekdays and second job - to run full scans on weekends.