I just encountered [this Reddit post](https://www.reddit.com/r/linguistics/comments/1gc5jc/12_old_words_that_survived_by_getting_fossilized/) which revealed the following answer to my question: see 12 [herefrom](http://www.mentalfloss.com/article/51150/12-old-words-survived-getting-fossilized-idioms).


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##12. shrift

We might not know what a shrift is anymore, but we know we don't want to get a short one. "Shrift" was a word for a confession, something it seems we might want to keep short, or a penance imposed by a priest, something we would definitely want to keep short. But the phrase "short shrift" came from the practice of allowing a little time for the condemned to make a confession before being executed. So in that context, shorter was not better.