Organizing document types in Sanity Studio using Structure Builder

As we're expanding our use of Sanity, we're getting more and more document types, and the list of "root folders" to the left (under "Content") in the Studio keeps growing. Is there some declarative way to group things and not have as many options in this list, or will I have to look into parts to do this?

You can use the Structure Builder to customise the structure (heh!) of your documents and group them however your want https://www.sanity.io/docs/overview-structure-builder