Chris Webb shares some thoughts:
If you read this post that was published on the Fabric blog back in July, you’ll know that each Power Query query in a Fabric Gen2 dataflow has a property that determines whether its output is staged or not – where “staged” means that the output is written to the (soon-to-be hidden) Lakehouse linked to the dataflow, regardless of whether you have set a destination for the query output to be written to. Turning this on or off can have a big impact on your refresh times, making them a lot faster or a lot slower.
Chris shares a simple example of when staging might not be reasonable. This is going to be the less common scenario, however.