Do I live in the rust belt? No.. But I work on 30-50 year old cars all the time, and with our humidity we get rust here. We also get rust belt cars from all the snow birds moving here.
That said, I have a handful of 6 point wrenches(Craftsman makes some, or they did).
Do I use them? Sometimes, but never because its a 6 point, just because it was the first one I found and I had the range to use it.
Fact is, 85% of the time if a head is rounded or rusted where a QUALITY 12 point wont work, a 6 point won't either. The flat offers very little to grip to. 6 point or 12 point, once the corner is gone the ability of the flats of the fastener itself to resist the stress is pretty low.
Therefore once its too round for a 12 point Im usually right to vice grips and or heat.