My Ford Trucks charge 14.2- 14.5V and it is hard to run the same battery for longer than 6 years.
The conclusion you reached, that higher alternator voltage is responsible for lack of battery longevity, is not the same as the majority of automotive engineers designing 12 V systems.
The optimal charging situation is to recover from high starter draw and return the battery to a full SOC as quickly as possible.
FWIW, the original, slightly abused Motorcraft battery installed in my '03 Ford Superduty was replaced at 10 yrs., one month.
I'm sorry to hear that the OP discounts the information related before his last post. There are many members on the Forum that have rich technical experience. Maybe he's in search of a different answer?
However, I don't discount observation and if CD noticed an abnormality in his gauge readings, an investigation would be prudent. Since alternator output is proportional to battery acceptance, a tuneup of the battery and the connections would be my first step. I'd suggest to remove and clean all the connections to the battery, clean up the case, and charge the battery overnight at a small amperage charge. At the next start sequence, the gauge may read that the voltage is lower. That would indicate that the battery, in the previous observed abnormality, was slightly discharged more than normal and the alternator was operating correctly.
