I think model-building is very important. Mock-ups and sketch models to show how something works, , its interface, its construction, it’s proportions and as platform to “think-through” a design hands-on I’m finding reduces iterations in the product development cycle while also being a good way to present along with sketches, renderings and illustrations to non-designers of the team/company the design intent. It’s helped me after sketching out the general idea of a design to delve deeper into its details. We mock-up and create models for all of our designs at my company and use outside model shops for the high-fidelity appearance models.