Ah, good to hear about 4 days a week being considered. Some time back I managed to pass a message to someone within Amtrak who said that he managed to pass it through to the execs --- explaining *why* even 4 a week is significantly better for the traveller than 3 a week.
With 4 a week, you may have to move your scheduled travel date by one day in order to take the train. This is a pain, but often doable. With 3 a week, you may have to move it by two days, and that's just much much worse for customer scheduling; it's often too much. This is a large part of why I've never attended a certain convention my friends often go to in Indianaopolis. The convention schedule hits the Cardinal schedule wrong and would require two extra days in Indianapolis on each end (!), which is just not going to work for me (four extra days around a four day convention!). One extra day on each end would have been manageable.
In short, the convenience for the traveller is based on the *worst case scenario* for how far away in the future the next train is from the time they actually want to travel. You want to minimize the gap between trains.
I am glad to hear that this message may have gotten through, so that on routes where cuts may be necessary due to staffing shortages, they will try to pay attention to customer needs.