Is @Mention necessary when replying to someone in a comment?

[US Source Deployment PESdev Account]

When REPLYING to a Comment, and you want to ensure that the person whose comment you're replying to is notified, is it necessary to @mention them in the reply, or, in all replies does Confluence automatically notify all parties @mentioned in the original, upstream comment(s)?

[Brant Schroeder]

If the person is watching the page then they will be notified.  Otherwise to be safe an @mention is the best way to ensure that they get a notification.

[Rex Card]

Does the user get a notification each time an @mention is placed in the comments?

For example I create a page (and save) and @mention a user in the first comment. I assume they get a notification.

If I update the page again (and save) or not update the page can I create another comment with an @mention and assume the mentioned user will get another update?

A better question might be for each unique comment created (not edited) with a common @mention will the user receive a notification for each comment?