As far as thru freight goes, I would say Wednesday, Thursday, Friday and Saturday tend to be the busy days. The different roads seem to like getting the traffic into their destination no later than Sunday so the locals can take it to the customers.
As far as the locals go, Monday and Tuesday are the busy days. With the traffic that arrived, they get the stuff out to the customer on those days.
The locals tend to have Sundays off.
Amtrak runs seven days a week.
The high priority traffic can run six or seven days a week depending how hot the stuff is.
Hope this helps.