A framework for judging whether a new bet represents a company's next major S-curve of growth, or is merely an enhancer to the existing business. Biddle cites games as a candidate next S-curve for Netflix, versus advertising, which he judged an enhancer rather than a new S-curve. He estimates a true S-curve bet takes 5-8 years to mature, so the framing should set expectations and investment timeline accordingly. Related to Growth-Wave Succession Principle and 'Walk' vs. 'Run' Framing (Staged Bet Rollout) for how enhancer bets get staged.
Casey Winters adds a concrete timing constraint to S-curve evaluation: because new products typically take 1-3 years to reach PMF, a company must start the second product well before the core product's S-curve visibly asymptotes — not once growth has already stalled. Waiting for the flattening to become obvious in the numbers means the second product arrives too late to matter, since the multi-year runway to find its own PMF has to happen concurrently with, not after, the core product's decline. This is the mechanism behind the second-product-timing thesis: model the S-curve, forecast the asymptote, and back into a start date.
Casey Winters frames this as a forecasting discipline applied to your core product's own growth curve: model the trajectory of your core product to predict when it will asymptote regardless of further optimization, and start investing in a second product 1–3 years ahead of that predicted asymptote. Waiting until growth has actually stalled guarantees a growth gap, since a second product itself needs runway to reach its own PMF — recall that marketplace PMF alone can take ~4 years. As Casey put it: 'the best time to get started is, you know, today; the second best time was three years ago.'