planning – Agile approach (vertical slicing) in ETL/ELT development

agile/vertical approach in ETL development

The question is: what do you think about using agile/iterative approach in ETL/ELT data warehouses/data lakes/lakehouses systems development? I often find that many business analysts / project managers tend to plan ingesting all data first, then building all semantic data and other horizontal layers only then build reports and go to the business. My experience is that ETL development is the area where agile approaches can bring most value to avoid rework risks. I have drawn the diagram in endeavour to make the point and to use this as an argument for vertical slices planning as opposed to horizontal ETL/ELT implementation.