Establish a single, blended CAC target across all marketing channels. As long as your total spend stays below this number, you have the flexibility to continue spending and experimenting with new channels without being beholden to the short-term performance of any single one.
Standard attribution models often fail to credit upper-funnel activities. A blended CAC mitigates this by focusing on total investment vs. total customers, implicitly valuing channels that influence conversions even if they don't get the final click. This prevents prematurely cutting channels that assist others.
Using a blended CAC doesn't mean ignoring individual channel performance. Use the blended number as your high-level strategic guide. When it rises, dive into the siloed, channel-specific metrics to diagnose the root cause of underperformance and make tactical adjustments.
Don't combine branded and non-branded search when calculating channel CAC. Branded search converts users who already know you from other efforts, making its CAC artificially low. Separating them is crucial to accurately assess how well your ads are acquiring truly new customers.
Rather than isolating test budgets, roll new channel experiments directly into your overall blended CAC calculation from day one. All spend is part of acquiring customers, and this maintains a holistic, accurate view of total marketing efficiency. Small test budgets are unlikely to skew the overall number significantly.