You mean something like having ~/well-known-stuff and under that having a 54f757919a5ede5961291bec27b15827 directory with the book scanning scripts and so on?

That could work fine, but generally the directories I've used this on are directories that I want to have somewhere else, and with a reasonable name. Usually the directories came first and various other things in fixed relative positions were using them, and then later I wanted to use them from elsewhere and added the ID.

I suppose ~/well-known/stuff/54f757919a5ede5961291bec27b15827 could by a symbolic link to the original.

The mdfind approach does have the advantage that if I reorganize things and move the directory it keeps working.