The new tension which is being applied must be evenly distributed throughout the entire length of the string. It therefore becomes necessary to hit the key in precise unison with the turning of the tuning pin, which enables the new tension to find it’s way through up to five different twists and turns or tension points. This will help to insure that when the notes are subsequently struck hard viz. by a concert pianist, the piano will retain its tuning.
When there is a conversation going on near or next to the piano there is a temptation on the part of the tuner to be concerned about disturbing the conversation, and as a result the tuner could become less emphatic about this important aspect of tuning.
Moral of the story:
Stay away from the tuner when he is tuning the piano or at least don’t talk !