You're right, I should correct that.

It should say that I have never seen room for an additional bag in the overhead by the end of zone 1 ON ANY OF THE 100+ DELTA FLIGHTS I'VE BEEN ON TO/FROM ATL IN THE PAST YEAR.

In fact, the GAs will always require zones 2-3 (formerly 3-4) to check any bag that won't fit under the seat. Of course, that means they let the zone sky or zone 1 passengers find out the hard way that the space is already gone, then have to fight their way back to the front of the plane. Again, I can only speak for EVERY FLIGHT I'VE BEEN ON.

If you're going from ATL-BFE then you may have better luck.