My general view of the deck heights is that for the corridors, they need to be tall enough to support the periodic cross-panels, and the other rooms can be lower (specially the ones that include structural members). This would mean that if you had to cut through the floor to get to the next deck, you'd want to do it where you'd have a corridor below.
I can't recall off hand, but I seem to recall a small opening between decks in some of the early episodes (like Charlie X
) that some crew members were working with. Those showed a minimum deck thickness in the corridors of 6 to 8 inches (of course there wasn't actually another deck below on set).