When you have three or more books you are reading, without finishing any of them, and you find a new one.
Standing on the backs of a bookshelf.
You have a task to do, alone, during non-office-hours, and
technically everyone goes well
except that the last step - the one that doesn't count against the official done-by-time anymore - takes 6+ hours instead of the expected 1-2. And
could have been left running unattended if only you had suspected
beforehand that you might want to walk away from it.