I believe they could refill quickly enough that pushers on the same train could refill from the same troughs. They were quite shallow, as they had to sit on ties. Ties could be reduced in height, but only a bit.
I have posted these before on the New York Central fallen flag forum, but it seems they are appropriate for this thread. Here's a shot (New York Central photo) of a mechanic inspecting the tender water scoop on a NYC tender. And here's a Harold K. Vollrath photo of a New York Central hotshot with Niagara power taking water on the fly. How would you like to be standing next to that track, eh?
I have a NYC video from Heron Rails that shows a couple of different trains using the water scoops. It is some neat footage. Also, didn't the Pennsy also have some engines with water scoops and some sections of track equipped with water troughs?
Yes, the Pennsy used troughs, at least between Harrisburg and Pittsburgh. Someone mentioned that the B&O did also. There may have been others, but I don't know.
The article linked to back on the first page says that the Reading, New Haven, Maine Central, and Milwaukee Road (!) had track pans.