Battery blowing voltage regulators "why"

I don't know. Intermittents are "hell" I've written a BUNCH of charging systems on this site. The "usual suspects."

Of course you need a good battery. ALSO SUSPECT the battery mounting, the types of roads you travel (bumps / washboard) IE possible damage to the battery from shock. The battery must not bounce around "in there" and move around in the tray. It must be solid and tight, or you will "beat it to death." (Bungie cords don't hack it)

Field current. Check alternator field current and endeavor to buy good quality regulators. That is harder now, even at NAPA, who should have their heads dropped in shame. Echlin and Standard / Blue Streak at one time were "the" quality standard. No more

"All other" wiring considerations...........

Might be time to put one or two accurate voltmeters "in the system." If you mount a couple under the dash, you can run wires to different points at different times. One direct to the battery, and move the other around "once a week" LOL

Make sure the charge wire is large and has GOOD terminations, which is the big downfall of OE wiring, and IS the subject of the famous MAD article

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

If you do nothing else, even temporary, run a nice big huge charge bypass wire from the alternator stud direct to the battery. This will require a voltmeter, as your ammeter won't work. One way to do this with common available parts is to parallel about 3 no 10 wire, as you can get terminals and wire from the parts houses.

Since you are having regulator problems, this might indicate a short right in the field circuit. Maybe you should inspect that field wire THE ENTIRE LENGTH from the regulator F terminal to the alternator.

Of course the regulator MUST be well grounded.

And, double "triple" check voltage drop problems.