Palladium white golds are a LOT more forgiving than nickel based
white golds. Among other things, the palladium white golds are
much slower to “age harden”, if indeed the do it at all. So
letting an item air cool vs. quenching it will make less
difference. And, these alloys are a lot less prone to cracking
in any case. Nickel white golds need to be chilled more quickly
simply to avoid their starting to age harden on slow cooling.
Yet at the same time, if chilled too quickly, you can crack them.
Thus the recommendation to quench, but only after the metal has
cooled below a low red heat (about 900F). Letting the metal air
cool will still have stress relieved the metal, and will be
still mostly soft. It just won’t be as soft as it can be. In
some cases, though, the risk of cracking the metal with the shock
of quenching is of more concern than the need for absolute
softness. Quenching in alcohol helps also.
As to theoretical right ways? In all of jewelry making, the
theoretical right way to do anything is “whatever works best for