Before Etsy revamped the Wedding section (sniff, sniff) I use to list or renew at least once a day.
If I have an item that is in a different category I'll renew once a day or so. If my item is in the Wedding category, I'll renew once in awhile.
I got this from an Admin. post
"...For example, renewing your items won’t have the same effect with relevancy as it did with recency. While recency is still a factor in relevancy, it's not the only one."
So as long as it's "still a factor.." I'll continue to do it.