Are the episodes on the discs complete, or are "library tracks" put at the end of a season set, and not edited into the soundtrack for an episode?
All that's included for a given episode are the original cues that were written for that episode and recorded as part of the recording session for that episode. Library tracks that were recorded separately are included at the end of each season set.
After all, "complete" soundtracks including all the recycled stock and library cues as well as original cues for every single episode would be something like 30-40 hours of often-repetitive music, and the set would have to be twice as big and twice as expensive for no reason. Each distinct cue is only included once on the set, in its complete and original form, either as part of the episode it was written for or as a separate library cue if that's what it was.