There are about 100 FOs in ATL. 18 months puts you in the top 30%. That should get you Sundays off. There are shorter pairings, however it looks like a lot of 3-4 days. Presumably because there are a lot of commuters and that's what they'd prefer.

They actually do poll the pilots at each domicile to see what they want. In SLC it's predominately shorter trips, while bases with a lot of commuters get the longer ones.