Generally true. Most hopper loads from mines were “peaked” with a fairly uniform ridge down the middle of the load. Some hoppers were designed to peak the loads right to the end wall of the cars to allow for more capacity…
I remember old timers telling me that when they were kids one the their chores was to walk the rail with buckets to bring home the coal that was dropped.
This was in Dunellen, NJ.
Dunellen grew from its start in 1867 with the construction of a railroad station, CNJ.
Lots of coal roll thru this state from the CNJ hauling to Jersey City, NJ.
The more you loaded the better profit for the RR back then.