The biggest risk in document revisions is not "what was changed," but "which version did the other party actually confirm." The common problem is: the seller ships according to revision 3, while the buyer thinks they're still on revision 2, and only realizes the quantity or terms are wrong when the goods arrive.
To avoid this, there are two key points: First, save a PDF snapshot each time a document is sent out, so "what was sent at that moment" is fully traceable. Second, if the other party requests changes, the revised version should be compared line-by-line with the previous version, so both parties clearly see what changed this time instead of reviewing a new document from scratch.
Before shipment, it's best to do one final document audit: compare the final PI with the packing list to confirm that items, quantities, and terms all match, then proceed with shipment. This step may seem redundant, but in practice it catches many errors that would otherwise be discovered just before shipping.