Which of the 36 mechanics worries you most when you see it in other funnels?

The 'continue' button that lets you skip past the fine print without it ever appearing on screen. That's ¶84 in the PDF Guru case. It's not ambiguous — it's a button placed specifically so that a reasonable user following the natural path never sees the renewal terms.

The five products share one playbook. What does that tell you about how this was built?

It tells you the funnel was the product, not any of the apps. The content was the acquisition vehicle. The recurring billing was the business. That distinction matters because it means every person on the growth team knew exactly what they were optimising for.