To mail or Not to mail? How long should I continue to mail?

[Benjamin Blackburn]

So lately I've been hearing/ reading forums about individuals continuing to mail a prospect forever, until they call in and request to be taken off or become a motivated seller.  I'm just curious on you alls thoughts on this.  I've been sending direct mail for about 6 months now(Just started tracking results and testing after two months with 2 calls) and planned on maybe tapering off old lists slowly.  Would I be wrong to do that?

Any input would be highly appreciated.