Once I made journeyman, in the 80s, if the boss caught you digging someone’s getting fired, “I don’t pay you $20 an hour to dig holes”.
I worked on commission, 50% of the job that wasn’t spent on materials and 10% on materials, if work was slow and I could do my own digging between service calls then I enjoyed the break and pocketed the money, later I was an owner and the same still applied, if the time was available it was pleasant work and kept one in shape, plumbers do tons of digging anyway doing research, investigating, and repairs, at least trench digging was usually dry and during the day.