There's no single correct number — it's stage-dependent. Early-stage companies still finding product-market fit often need to spend a disproportionately high share of revenue, or run pre-revenue entirely, just to generate enough signal to learn from, while established companies with predictable growth typically settle into a more efficient, lower percentage once channels are proven. Industry surveys commonly cite ranges in the high single digits to low double digits of revenue for established B2B and consumer companies, but treat that as a loose reference point, not a rule. Kando frames this as a per-stage decision with clients rather than handing over one blanket percentage.
The better question is usually not ‘what percent’ but ‘what's the marginal return on the next dollar’ — spend up to the point where that return still clears your target payback.