How to know if your innovation method, tool, workshop, framework, or book works?

When using it or applying it to a real innovation project, it should lead you to a price for your innovation. Not a pricing strategy or a price range, but a price.

If it doesn't scrap it.

• And yes, this price will only be preliminary. This is why you need to prototype and test with your market. Not for technical reasons and check if your actual innovation doesn't blow up in the face of your customers – which, admitedly is necessary to do well ahead of time – but to check if you get your target customers to pay for your innovation value add.)
• Consequently, when people ask me why I don't like or trust design thinking, it's the only reason I need.