What it is

When you're stuck on a problem or circling the same frustration, ask yourself why? five times in a row. Each answer becomes the starting point for the next question. By the fifth round, you've usually moved past the obvious surface stuff and landed on the actual root cause.

Our take

This comes from Toyota's engineering culture, and it works just as well on personal problems as it does on factory floors. The first couple of answers are almost always shallow — the kind of thing you'd say on autopilot. The value is in rounds three through five, where things get uncomfortable and honest. That's where the useful stuff lives.

Worth doing if...

- You keep solving the same problem without it staying solved

- Your frustrations feel vague and hard to act on

- You want a thinking tool that takes five minutes, not a therapy session

This is probably not for you if...

- You're already clear on the root cause and just need to act

- You tend to over-analyse — five rounds of why? can become rumination if you're not careful