Let’s confine this question to acquisition and customer development activity. Let’s also broaden it to include email and direct mail.

The answer is, “As often as the advertising continues to earn an appropriate return on the investment.”

For fundraisers, it is not uncommon to mail the core names up to 24 times a year. On the other hand, acquisition appeals may go out to control lists from 2 to 4 times a year before the response rate begins to drop to an unacceptable level.

With the advent of cheap email communication, however, it is no longer enough to evaluate contact frequency based on cost. If judged on this basis only, the outcome will hurt the brand. Over-communicating with existing customers has become a real temptation for many companies in the presence of a low cost medium like email.  

For direct mail, the financial barrier restrains excessive communications.

One of my BtoC clients has a small target market and needs to generate relatively large volumes of leads. At about the 8% penetration level, their response rates began eventually dropped from 1-2% to .1-.2%.

As penetration deepens, the cost per lead increases dramatically.

Unless this client finds a way to increase the size of its database or create new product offerings that create demand with existing names, his business will decline for lack of new prospects.

In your experience, when does high frequency begin to damage the brand or when does it no longer pay to mail?