Battery drain issue

I just don't know then. Wondering if maybe alt' rpm at idle is the issue? Wondering if battery cables are good? Chassis ground jumper(s) good?
Years ago a friend had repeating regulator failures in a 68 Nova. The lug/terminal on the end of the ground cable was properly bolted to the block. With a slight tug the wire pulled right out. If not for a bit of oily electric tape wrapped on it I wouldn't have found the problem so quickly. Remembering other cases that were silly simple faults, like paint interrupting ground path for example. Good hunting.