Some more examples: the Crescent, four sets; the Silvers, four sets, the City of NOL, 3 sets.
Look at the City of NOL for example. IF IF it went only from CHI to MEM, for example, there is plenty of time to be cleaned and turned in Memphis, such as two sets would suffice. But.....the southbound arrives NOL two hours after the northbound departs so obviously it needs another set.
There used to be a TV commercial which said, "It's 11 pm, do you know where your children are?
So do this, "It's 9 am, do you know where the Crescent is?
Well, one set just left NOL going north.
Another set just left Atlanta going south
a set is nearing Alexandria heading north
fourth,a set is sitting in Sunnyside yards waiting to go south this afternoon.
(PS I know there is construction south of ATL this time of year but that is not relevant as I am only referrng to normal operations).
In years past the Crescent has been known to carry some cars just NYC to ATL. That would have been handled by three sets. It has also been known to carry from WAS to ATL, that would have been two sets. These in addition to the usual NYC to NOL.