I don't know your softener, but I suggest that you get a softness testing kit. If you have some hardness coming through just before regen is expected, program to use more salt. If no hardness, try setting for a little less salt. A few grains of hardness leaking through during your testing will not be so bad.
The Hach 5-B test is well-recommended, and I am glad I bought mine. Buying directly from Hach can be good, although if a neighbor wanted one also, you could share the shipping charge.
Alternatively, make your own test with a dish soap solution. Calibrate by mixing soft water with a few drops of hard. Shake, and look for suds that persist for a few minutes. Your procedure should be able to detect small levels of hardness. So expect a mix of 90% soft and 10% hard to test at about 1.3 grains of hardness. If your test can distinguish that, then that should be a good-enough test.