Locking nuts are officially only meant to be used once and tightened up in one turning action.
In the aircraft industry they must be only used once!
The nuts were I think originally included with the seal but not any longer! That was probably when they were to replace the earlier seal design which used non locking nuts.
So the considered answer must be that its not thought to be important enough to change them unless a specific problem is found.
god knows, its not as if they are expensive and can be used for other work. it does semm odd which is why i asked. they even come with the gasket kit so its not as if they need to buy extra.
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