Open the final merged PDF in a viewer other than the editor. Verify section order, page count, first and last page of each source, duplicates, rotations, links, searchable text, and any sensitive page that should not be shared.
If you compress afterward, repeat the checks on that exported copy. Keep the original files until the recipient confirms the packet works. A successful merge action is not proof that the document is complete.
How many source files should be represented?
Akousa