Battery cut off switch

Doug, I don't believe that is true if you use a 4 post (DPST) switch and a three wire alternator. The entire reason for doing so is to avoid a separate (hot) alternator line back to the battery

A "one wire" setup might be a different matter.

But your post brings up one of my favorite "fake" testing procedures, that is, do NOT ever remove a battery connection on a running engine.