Back when I began, we tore down pumps every season to check wear. Now with better materials and monitors, it's mostly just watching screens. Kinda miss getting my hands dirty.
My old boss made us crack open the flow meters twice a year no matter what the readouts said. Found a hairline crack in a housing once that the pressure sensors never flagged. Sometimes the old ways catch what the screens miss.
My buddy's team relied solely on their pump monitors for months. They finally opened it up and discovered severe cavitation damage the sensors never picked up. @the_jesse has a point about trusting gauges too much.