Bash scripting: Last line - "exit" - necessary?

another basic, innocent question: When you make a bash script, you could close it with, you could type in as last line of the script,

,

echo "Hello world!"
exit

, is it advised, should one generally close a script with

? I could imagine, that basically from IT-security perspective it's better to set a definitive end to a script. I could imagine, that otherwise it would be an open end, never closing, always luring in the background, and potentially could be exploited somehow, or simply just wasting resources…