I have never seen anyone using the pin/string setting technique that
I am about to describe used by anyone other than one person who tuned 
my piano.  I have copied his method and find that it works very well.

In addition to playing the key for the shard being tuned very hard
while operating the tuning hammer, he also strikes the key _very_ hard
after it is at pitch and then checks again.  This is not just repeated
hard playing but almost brutal pounding with the index finger as hard
and quickly as you can.  I was afraid that the action could not take it
but was assured that it is not a problem and have seen no damage from
using this method.

A single hard strike settles the string and pin better than any other
method.  If the string is still in tune after this assault it will stay
in tune for a long time.

Best regards,
Spencer Chase
Garberville, Calif.
http://www.spencerserolls.com/