"My ROAS looks healthy, so my ad spend must be working."

Looking at ROAS or CAC alone, without checking what those customers are actually worth over time.

In one analysis, blended CAC was $172 against an average customer LTV of $115 — an LTV: CAC ratio of 0.67. Every paid channel (Facebook, Instagram, Google Ads) was acquiring customers at a loss (ratio 0.32–0.50) and churning them faster, too. Meanwhile, Email and Referral were sitting at 1.95 and 58(!) — essentially free growth being ignored.

Before increasing any ad budget, check LTV: CAC by channel, not just ROAS. A channel can look efficient on spend and still be destroying money on retention.

This is the exact breakdown I'd run for any store spending on 3+ paid channels.