A product is a path for the reader to take them from where they are now to where they want to be.
Each product must be designed with this in mind.
Each product sales pages must spell this out, even with diagrams.
Each book introduction must spell this out and each book conclusion. The parts of the book are the big stepping stones on the path. The chapters of the book are the small stepping stones.
Too many steps can be daunting to the reader, they may not want to take your path.
Steps that are too large, mean that some readers won't make it.
The product is also a barrier between where they are and where they want to be.
Make it as easy to climb as possible.
You must clearly know and define where the reader is, what they want, how they will get what they want using your product and what it will be like once they get there.
Without this all clearly known and spelled out, the product will not have a good fit.
It does not matter if you are wrong, because you can change it. You can change the marketing and the copy based on what was learned.
This idea of a barrier or a path also applies to each tutorial.
Meet them where they are and guide them to where they want to be.