I'm not a lawyer, but my understanding has always been that the copyright notice isn't required at all. If you get into a dispute over the ownership of something, you just need a way to prove you're the actual copyright owner. I don't see how a small line of text on the page will help you do that (especially since you can arbitrarily change it whenever you want).
I keep mine up to date on my sites just because it's basically a staple of modern web design. Not having it would be weird, and having it out of date would probably confuse people.
Yeah, the git history will back me up in any actual copyright dispute. I just have the date in the footer to keep my website from looking old and stale.
Git history is as strong as evidence as a copyright string. One can forge a repo with dates they need and upload it to github. With a well-versed arbiter you’ll probably end up looking at internet archives.
I keep mine up to date on my sites just because it's basically a staple of modern web design. Not having it would be weird, and having it out of date would probably confuse people.