When I started with digital photography, I used to keep a copy of ALL the photos I took on a backup drive, "just in case". As the years have gone by, I have become more ruthless, permanently deleting the very worst technical shots (severe focus & exposure problems), then deleting most shots that were not sharp, and then later I started deleting "good" photos because they were duplicates or uninteresting.
Apart from photos of family or maybe travel, etc., there are very few pictures that I ever go back to.
I realize this process is very personal, but are there any guidelines or rules of thumb as to deciding which photos to keep and which to trash?
A related and possibly even more inappropriate question; What percentage of photos does the typical serious amateur end up keeping?