Trained by ear, still working by ear
Piano tuning is mostly invisible work. Done well, nobody notices it happened - they just notice the piano sounds right again. That is the standard: leave quietly, and leave the instrument sounding like it was never any other way.
Training was a three-year apprenticeship under a technician who served the same neighborhood for four decades, tuning entirely by ear rather than a meter - listening for the beats between two notes slow to a stop, one interval at a time, until the whole piano agrees with itself.
Now working the same routes, one house at a time, with the same rule: explain what was found, explain what it will take, and never leave a piano sounding worse than a plain conversation about it would have.
