EDIT: As an aside, can Accept / Reject ping-pong?
If the edit has a single problem, but is otherwise a good edit, I will open a new window on the editing question, accept the edit, refresh the new window, and fix the single problem.
If the edit has a number of problems, or changes the technical content of the post, I reject the edit. If the post still needs editing, and I have time, I edit the post myself.
More than half of the tag wiki edits that I approve have to be further edited. Which is not a complaint, by the way. There are many tag wikis that are getting filled in with good content because someone (no matter their rep) cares enough to post a tag summary and description.
You now have the option of "Improve", which would address this issue.