Good question and we have seen this extraction workflow a lot in financial services. We just added table mode to the product (select table in transformation parameters) where we extract table structure in the documents that match that schema. So 1 file map to N rows where N is all the row in the table.
For instance, I have 100 pdfs, each with 10-100 individual products listed (in different formats).
I want to create a single table with one row per product appearing in any of the PDFs, with various details like price, product description, etc.,
From what I can tell from the demo, it seems like 1 file = 1 row in Trellis?