The accepted answer to this question suggests that community wiki is deemed sort of a legacy feature that serves no real purpose anymore, as people are supposed to just edit additional information into existing answers, if they feel that a given answer is good but is missing "something".
Both, Jigg and Pete L. Clark remark that this in practice basically never happens (essentially all edits are just grammar or spelling fixes, with the occasional do-over for clarity and style). This is also my impression - I have been reasonably active on the site in the last few months, and from the top of my head I cannot remember a single case where I have seen an edit that actually added content to an existing answer. Personally speaking, I would also see this as highly inappropriate, as there is no guarantee that the original author even endorses a given change. Pete L. Clark goes into detail in his answer why people seem reluctant to do anything but minor style edits to other people's answers.
My question is now as follows:
If we encounter a question that already has one or more answers that we consider really good, but we feel some minor-ish detail needs to be added. What is the right way to do it?
- Post a comment and ask the original author to edit it in.
- Edit it in directly.
- Provide a new answer, which starts with something along the lines of "The existing answer by XY is good, but ...". I have done something similar myself today.
Option 1 is ok but cumbersome. The question linked at the top seems to suggest to me option 2, but how do we guarantee that the original author even has the same opinion on the topic? Option 3 seems to be the common way how it is currently done (my impression at least), but brings us close to community wiki territory.