LTV to CAC is easy to game and easy to misread

A healthy LTV to CAC ratio can hide a cash flow problem that quietly stalls growth. If it takes eighteen months to earn back acquisition cost, a business can look profitable on paper while running out of runway in practice.

Payback period forces a more honest conversation, because it is measured in the same unit finance already cares about most: time until the cash comes back.

LTV assumptions are where the gaming happens

Extend the LTV lookback window far enough and almost any acquisition spend looks justified. Payback period is much harder to dress up, because it is anchored to cash already collected rather than revenue projected years into the future.

Use both metrics, but let payback set the pace

LTV to CAC is still useful for long-range planning and comparing channel efficiency over time. Payback period should be the metric that governs how fast you're allowed to spend right now, because it reflects the cash constraint the business actually operates under.

Shorten payback before you try to raise LTV

Improving onboarding speed, upsell timing, or initial plan design to shorten payback usually compounds faster than trying to stretch retention further out. A business that gets cash back sooner can reinvest it sooner, which is its own form of growth.