While never guaranteed, it also matters where/what you are on/going to. Generally, if you're on a CRJ200 then you're going to go to D because many of those gates have been reconfigured to smaller sizes to fit more of those types of airplanes in them. C is also often used for larger regional jets. A & B are entirely Delta and are almost exclusively mainline. T are the most desirable gates for people originating/terminating in Atlanta because those are the closest to the terminal and don't require a train ride (Legacy American flights still run out of T with it's own separate dedicated baggage claim but if you're on legacy US Airways (e.g. Charlotte, Philadelphia, DC) then you're going out of D). Before COVID, you would see flights that had a lot of originating/terminating traffic on them such as LaGuardia but everything is so different now. They still run a few flights out of E and if you're arriving in the international terminal then you will be a pretty lengthy train ride away. Yes, you can arrive in the international terminal on a domestic flight because the plane is turning back to international.
Regardless, the layout is T, A, B, C, D, E & then international. Every concourse between T & E is about a 2-3 minute train ride between stops and the trains run every 1-2 minutes. The train will put you out the middle of the concourse...how quickly you can walk to the ends of them is up to you.