Cant provide much help here. My well experience is in repair not deisgn. I know how to get mine working again thats about it. (joking. sort of.)
But in short when watering a bunch like filling up troughs, it isnt hard on the pump to run for a long time. It is hard for it to cut on and of repeatedly. So for a single large fill a 20 PT vs a 52PT or even a 5 PT doesnt really change the equation.
