Big PDFs are mostly big because of the embedded images. Ready Done rasterises every page at a quality you choose, then rebuilds the file — cutting size dramatically, especially for scanned docs.
Image-heavy PDFs (scans, presentations) often shrink 60–90%. Text-only PDFs see smaller savings — but you can still tune them down. Note: compressing this way replaces the searchable text layer with images, so if text selection matters, keep a copy of the original.
Compress after a merge, before a zip, or alongside strip metadata when sharing externally.