My first job was also at RadioShack but back in 1995. We were all focused on batteries, adapters and consumer electronics. and cell phones were starting to be a big deal as carriers started subsidizing phones.
I remember the "Battery Club" you could get one free battery a month I think. They gave you a little card and would punch a hole in it for every battery you got. My dad would stop in every month to get his free battery. I don't recall if any purchase was required but I don't think so.
In the 1960's, my brother and I would walk about three miles (over Red Mountain in Birmingham AL) to the closest Radio Shack. We would each get a free battery using our cards and usually we didn't buy anything. Eventually we became pretty good customers.
It wasn't; at least for me as a teenager in the 80's. Could have been a per-store policy, but the one in the Lockport suburb of Chicago and the one in the Winter Garden suburb of Orlando didn't.