Have you ever let long-cure epoxy mounts cure overnight, only for the setscrew to push into the mount when you went to load it into your grinder/polisher’s fixed specimen holder? When the epoxy is soft, the specimen isn’t secure in the mount or in the specimen holder, and proper grinding and polishing becomes impossible. The eight hour cure time for long cure epoxy means you can’t just whip up a new one; if something goes wrong, you’ve effectively lost an entire day as the replacement also needs eight hours to cure.
But if you left your mounts to cure overnight, shouldn’t that have been more than enough time? What could have gone wrong?