In my opinion, change it to 7 recs every 7 days. This way, you can use all 7 on one day and wait a week until you can rec again; use one a day; or any other combination of 7 recs within 7 days.
I don't think the overall limit of recs (over time) should change because, as someone said, there aren't many good topics anyway.
EDITED: More clarity.