Can you briefly expand a bit more on your system? My issue with typical folder hierarchy is that it kinda forces a file to only have 1 direct parent (i.e. the folder) or ancestry (i.e. the folder path)
Sometimes you come across a pdf or some document and it hits on several topics e.g. maybe an article may be related to topic A, B, and C. And also relevant to your projects X, Y, and Z.
Before Zotero and Obsidian, I wonder whether I should have a storage hierarchy independent of the topics and projects or I should simply duplicate the PDFs and put the copies in the relevant topic and project folders.
Now, I am thinking of just having a flat folder hierarchy to store the PDFs and yet remain accessible to Zotero and/or Zotfile. Then perhaps using @argentum plugin for mdnotes create a md reference to that PDF. Then the individual markdown notes for topic A, B, C, and projects X, Y, Z, all have links to the md note of that PDF.
So your experience may help me decide one way or another. Or perhaps even another completely different way of organizing