Deep document sets are easier to move around now. The full folder structure sits in a rail on the left of the Documents tab, in both the card and list views, so you can see where everything lives while the files stay one level deep. Picking a folder shows just that folder's contents, and the tree stays put, so hopping from Electrical to Mechanical takes one click instead of backing out and drilling down again.
One sort for both views. Sort by name, last updated, or date added. Name sorting understands leading numbers, so 01, 02 and 10 stay in the order you gave them. Folders stay pinned above documents by default, with counts in the section headers when a folder holds both, and your choice is remembered per project.
Drag to file. Drag a document or folder onto any folder in the rail to move it there. Dragging files in from your computer still uploads them, and now drops them straight into the folder you aimed at.
The path is in the breadcrumb. The folder trail lives in the page breadcrumb at the top, and the last crumb opens a list of neighboring folders so you can jump sideways without going up a level first.
Works on a phone. Below tablet width the rail opens as a sheet from the toolbar, and picking a folder takes you there and closes it.
One sort control, shared by the card and list views and remembered per project.
In the list view the tree also narrows the table to the selected folder, and double clicking a folder row drills into it. Everything stays in sync across views, so switching between cards and list keeps you in the same folder with the same order.
The same folder in the list view, with the rail scoping the table.
See Uploading documents for how documents get into a project in the first place.