I tried cleaning up some of my old zero-vote answers, and quickly ran into the five-a-day limit. I found this question with a nice accepted answer explaining why we have this limit, and how it would make sense to exclude zero-vote answers from the limit. However, the limit is still there, and I think it prevents some good clean-up efforts.
I think it would make sense to exclude all answers from the limit when the following three four conditions are met:
- The answer has zero upvotes
- The answer is older than 14 days
- The question has competing answers with 2+ total upvotes among them, or an accepted answer
- The answer does not have comments <-- added in the edit
Note that the up/down balance should not be considered to decide an exception from the limit: a question with one upvote and two downvotes should be subject to the daily limit.
The idea is to exclude answers that the author believes to be sub-par, and the community finds less valuable than their available alternatives.