I had at one point copied a large number of files between drives and did not use the -p and thus the timestamps were all set to the date of the copy.
I did not catch this, and deleted the source. So I 'lived' with it and have since changed many files.
Well, yesterday I found a good backup of many of those files and I want to restore them to their proper dates.
cp -p -u is exactly the opposite of what I want. I want to copy only if the source files have an earlier date than the destination files.
The source files are just an old copy on another drive that I found when cleaning up things...