ZydoSEO - 6:17 pm on Feb 16, 2013 (gmt 0)
Why not stretch your remaining link placements out? Start sending 10 every 3-4 days for a few weeks... then 10 every few months... Also, you can recontact those that never responded the first time you reached out to them.
If you have only been copying your competitors by seeking links where they have received them then you are likely missing MANY potential link placements. Look for patterns in the types of sites that actually link to them. Find other sites of the same type that are not linking to your competitors. They may link to you. Look for other sites that are complimentary yet relevant to your site, and reach out to them.
Use your head. Get creative. I'll bet there are literally thousands of other potential placements that you've totally overlooked.