We want answers to show their work, and of course we want answers to be useful. We've now got a fairly clear idea of what our standards are and what we should do with answers that fail on both counts.
Slightly trickier is answers that are useful but do not meet our standards for showing their work.
What action should we take with these?
I wouldn't want useful answers deleted even if they don't show their work perfectly.
For an answer that isn't useful, deletion is fine, but I think we need another way of dealing with useful answers that don't meet the standard of showing their work. I suggest we ask SE for a custom post notice or two that are used just for this purpose, that specifically mention that the post is otherwise good, something like:
This answer is useful but is not the kind of answer we are looking for because it does not show all the steps from the text to the conclusions
or
This answer is useful but is not the kind of answer we are looking for because it contains unsourced factual claims
