Rob,
About 15 years ago I worked out the best way to make leaflets work was to get your own distributors.
This way you can easily check delivery,it's solus and you build a relationship.
I found this 3 times as effective as putting in the paper.
I currently have 4 deliverers although one does'nt work the winter.
5000 and no response , I smell a big rat

Cheers,
Doug