Fifteen entries confirmed by testing, covering the PDF problems that come up most: oversized files, edits that don't actually edit, signing without a printer, merges that lose page order, and protection that doesn't protect. Each holds regardless of which editor is open.
Most oversized files are bloated by images, not text. Drop embedded resolution to ~150–200 DPI for screen reading rather than flattening through a virtual printer.
A white rectangle over old text leaves the original recoverable by copy or search. Click directly into the text layer instead.
Draw or upload a signature once, save it, reuse it. Faster than printing, signing, and scanning back in.
Drag page thumbnails into one visual strip and check order there, not just filenames.
An "open" password blocks viewing entirely. A "permissions" password keeps it readable but restricts editing.
Run OCR before editing a scan, or you're editing a picture. Set the correct source language first.
A black box over text usually leaves the original selectable underneath. Real redaction removes the data.
Most inboxes cap attachments around 20–25MB. Compress images first, or split a long document.
Most modern PDF forms have real clickable fields. A recognition tool can detect missing ones.
Sending an 80-page contract for one page invites confusion. Extract the relevant pages first.
Tables, columns, and footnotes are where conversions break. Check those first.
Combined files rarely share a numbering scheme. Run a fresh, continuous pass.
A side-by-side comparison flags a changed clause far faster than reading both end to end.
If a dozen files need the same step, find the batch mode before doing it by hand.
Save the original before editing anything important. The cheapest insurance against any mistake.