From Service manual;

Meter Delayed - Variable Brining
— The control regenerates on the day that the available volume of softened water drops to or below the
reserve volume. Regeneration starts at the set Regeneration Time. With the variable brining option
activated, the time setting for Cycle 1 is automatically calculated based on the volume of treated water
at the time of regeneration. Cycle time 1 will not exceed the original time setting and is never less than
1 minute.

I imagine this would mostly be useful with high capacity amounts with large reserves. Anyone have experience with this. I should setup a spreadsheet to play with the numbers. This is figuring the meter just uses a capacity/salt lbs ratio for when it would adjust the salt time down. Or does this work a different way?

*edit* What is the advantage or disadvantage of a second backwash?