If I have multiple instruments that use Kontakt Player (Dan Dean Solo Strings Advanced, Art Vista Virtual Grand, Garritan JABB, Stradivarii, A.I.R.) then they each have separate Kontakt Player updates in Service Centre.
Is there any reason to apply, say, the Kontakt Player 2.2.4 patch for each instrument or is it just the same patch?
I'm having serious stability issues with 2.2.4 on Leopard so I'm trying to remove any uncertainties.
It depends. If an update only concerns the player software, then no, there's no reason to apply the update once more. But, if an update also updates the library, then yes, you should run the updater, but you can uncheck all the software options and leave only the library option checked, if you have already updated the software to version 2.2.4.
In other words: run the updater in full for one of the libraries and uncheck the software options for the remaining libraries.