Mechanical gadgets may have particularly *****y pin blocks. A quality piano should be capable of holding tune at any volume.
OTOH, pianos that were not tuned regularly take a set with flat treble strings. A major pitch raise after 44 years of neglect required seven tunings for my 1940 Steinway to settle down. However, it was fine for two years after that; it has a great solid maple pin block.
Use of the tuning "hammer" to set the pin in may help, by driving it into the wood, but that also may damage the pin block. I prefer not to do that, I just keep tuning until the wires stretch the proper amount. I just did the second tuning of a 1950's Baldwin Howard baby grand last Saturday, center to upper octave pitch sagged pretty badly after three weeks. The late service pianist plays pretty loudly, but she paid (the church) for the original tuning. That was obviously the first time in decades. Other Howards I tune settle in after a couple of times, but I don't have very strong fingers. I don't have to play that loudly, the congregation out there in the country is usually 8 or so people. When I'm not there they use computerized music.