This is probably the most used document production technique that we come across. The problem is that you never go back to the original precedent which was so carefully reviewed for content, etc. Some jurisdictions have defined this practice as negligence. While you may proofread carefully for typos and missed "replacements", it is very difficult to know that a paragraph is missing - it was removed from the last file that you did. Frequently that same paragraph goes missing from the next six months worth of transactions done.
Wordprocessing made this practice possible. We're doing what we can to kill it.