Case number one is used for Packages and Modules, which require (no pun intended) that they end in (= return) a true value. You will also see this one, or any other true value ending packages in the middle of a file if there are several packages in the same one.
in reply to How to end a Perl script
Otherwise, just let it fall off the end when possible, and use exit in all other cases. That is by far the cleanest and most readable (and will continue to be the last statement even if someone by mistake adds code after BOTTOM:).
You have moved into a dark place.
It is pitch black. You are likely to be eaten by a grue.