Issue No. 17 | July 28, 2026

Intelligence for direct marketers in insurance, home services, warranty, and protection.

This Week: What Your Blended Retention Rate Is Hiding

THE NUMBER: 25%

Per Dark Sky Data’s cohort-based retention modeling, at an 8% annual attrition rate, a book of customers replaces roughly a quarter of itself every three years, just to hold flat before any growth target is added. That math applies whether the customer is a SaaS account or a home warranty policyholder acquired through a direct mail or digital campaign.

For direct marketers, the practical problem is that a single blended retention number can look stable while masking very different behavior underneath. A campaign that renews well across one acquisition vintage but poorly across another—or performs differently by geography—can average out to a figure that tells you very little about where to spend next.

THE OPERATIONAL ANGLE

Two campaigns can produce identical renewal rates and mean completely different things for your acquisition budget.

One holds its rate because the customers it brought in are genuinely sticking around. The other holds the same rate because continued acquisition is masking deterioration in the existing customer base. Blended retention reporting cannot tell you which is which. Segmenting renewal and cancellation behavior by acquisition channel, campaign vintage, and geography can. It’s the same cohort logic used in credit and warranty underwriting, applied to a marketing list instead of a loan book.

If your last channel review used a single blended renewal number, you are making budget decisions without knowing whether you are compounding a good book or continuously replacing a leaking one.

FROM THE BLOG

Customer Retention Metrics: Beyond the Headline Numbers

A blended retention number treats a durable customer relationship and a barely hanging on one as identical, which is exactly the distinction that determines whether growth is compounding or just being replaced. The post breaks down the retention metrics and customer classifications that explain the difference, including net revenue retention, customer retention rate, churn, expansion, and contraction.

QUICK HIT

At 12% annual attrition instead of 8%, a book replaces more than a third of itself in three years rather than a quarter. If you do not know your actual attrition rate by channel, you do not know which number you are closer to.

Until next Tuesday —

If you want to see what your renewal and cancellation data looks like segmented by channel and vintage instead of blended, reply here and we’ll book 20 minutes.