[mattigames]

Not at all; some simple effects like a stick-to-the-top header usually require cloning such element using JavaScript; and even if such effects are not needed right now they may be added in the near future, so no, there is not a single time where having an ID over a class makes sense.

[sametmax]

Since I'm more of a backend dev, I'm going to take your advice and try it on my next work. Let's learn something today.