Adjustable voltage regulators

There is absolutely no reason to have an adjustable VR. If the battery does not "run" at the correct voltage, fix the cause
No particular order:

1..Number ONE most likely is voltage drop in the harness---or ground--causing the battery to run high, even though the VR setpoint is correct
2...When checking, allow the battery to "normalize" and the engine to warm up--VR is temp sensitive
3...In some cases a bad battery---sulfated, EG
4...In a FEW cases the VR is actually bad--replace it