The PCM is always monitoring conditions as you drive and the way you drive for the conditions of a drive.
It then writes a predictive set of values in the tables of Tune for what the truck needs to do next at any giving time.
Removing the battery for 15 minutes is the way to reset the PCM and clear the KAM, if you experience problems, glitches,
even with the Nav unit and BCM module since it's tied into the PCM or even when you do mods to the drivetrain.
I personally don't bother with trying to save it, there will be default values in place.
The PCM will write as you drive and set a new predictive table every 50 miles anyway, and about 150 to 300 miles for a complete transmission cycle.
Putting in a fresh battery will probably need a PCM reset if your old one was that weak.
The only time you may want to not reset the PCM, is if you have to get it inspected right away and your state requires a OBD11 hookup.
It can take up to 6 drive cycles (50 miles each) with 8 hrs. of the truck being off, to complete the readiness of O2s, especially in the winter months.