Product Managers - Are you involved in day to day design of your products? If so, on which the most?

While I take care of the API/Integration design and implementation at my organization, there are other Product managers in my team that take care of UI & UX and User Documentation specifically. But, as most Product Manager roles at startups tend to be, my role is also fluid in the sense that I contribute to almost all of the above depending from time to time.

If my product is in the startup stage, I agree with all of these items.