How Do You Know a Process/Database/Document is Not Needed?

It seems to be endemic to bureaucracies that they create a lot of worthless, wheel-spinning work.  This can be extremely frustrating if you are a normal person who cares about doing a good job and making a positive difference in whatever you do.  I often find myself digging deeply into a database or document trying to get that last bit of data correct, or to improve it in some way, when suddenly I realize that I am probably the only person who will ever look at that data, and that my work will end up in a file somewhere, probably backed up in umpteen different corporate storage vaultsand servers as well, and will come to a complete zero as far as providing anyone with anything of value.  This leads to my subject: How do you know?