I can certainly play scales and in fact the layout of pipes in organs are sometimes chromatic, sometimes whole steps and sometimes in minor thirds. The key holder will play the appropriate scale to match the pipe order so the tuner isn’t running back and forth to follow the pitches.
We have had organists on staff and while it’s gratifying to hear some music on the instrument, I don’t need to hear that to know it’s in tune, regardless of temperament. Voicing is another matter, because when voicing, you’re setting the tonal balance of the various stops and you do need to hear them in context. Voicing is not a regular activity, being done during tonal finishing of a new build and once in a great while on an existing instrument.