Re: 3 engine rooms in the TOS Enterprise's engineering hull?
"But see the different nuances in the rationalizations, with a "pre-cracked inferior spare online with batteries" vs. "battery power until inferior pre-cracked spare can be brought online"."
Yes, and I definitely rather prefer to believe they were aware they (still) had a pre-cracked one they could use than to assume the spare was already damaged when brought aboard.
"The first duty of every Starfleet officer is to the truth, whether it's scientific truth or historical truth or personal truth! It is the guiding principle on which Starfleet is based! Jean-Luc Picard