This is very subjective advice. You could also endup with very patchy inorganically grown software when you dont do any upfront design. It depends on the scale

This is very subjective advice. You could also endup with very patchy inorganically grown software when you dont do any upfront design. It depends on the scale of your project. If you are adding a minor feature to the product vs if you are creating the datamodel of a new product. I would only show the datamodel once I have run enough experiments to make sure that it can support the next couple of years of application software