Building a model forces you to study and really learn the building. This is especially true when it comes to one of our favorite reasons for digital models: buildings of complex form. The computer allows you to make nearly anything look good. Only seeing the form in reality washes the lipstick off the pig.
If you can't build it at a small scale, you can't build it.
What works in concept doesn't always work in reality.
Scale matters. A lot.
That said, I also admit that I don't necessarily prioritize making a physical model of everything myself. If I am working on something that I know well and am very familiar or experienced with, I will often not make the physical model. I do always make a digital model though.
It can be truly tempting to work only in the digital and forgo building a model. It can also be embarrassing. I've had a table fail - I only made one simple study model and stopped the exploration there. Oops.
Actually, I'm going to re-prioritize it in my own work now. Thanks!