I think it wasn't just the schema structure, it was the API abstractions implemented in the schema.

If I remember correctly it was something about Shopify discounts, which can be applied multiple times and across different modalities- percent, dollar amount, etc. and what those were called in the API, and how they were represented and to which object they were applied to.

Then once I had figured that out, then understanding how to construct the query.

But of course my problem was more from the point of view of, "I just want to get x done". As the consumer of the API I wasn't as concerned about fully understanding the entire set of abstractions and schemas.