File-name order may not be document order
Names such as “final”, “final2” and “revised” are easy to mix up. Decide the document order first, then verify the merged result with page thumbnails.
Check portrait, landscape and page sizes
A landscape slide or differently sized scan between A4 portrait pages can be valid but awkward to read or print. Rotate and organize pages before merging when needed.
Submission files need a final review
Look for duplicate covers, blank pages, missing signatures, wrong orientation and a final file size that exceeds the submission limit.
Keep the source PDFs
You may need to replace only a few pages later. Keeping the originals lets you rebuild or edit the relevant part without starting over.