I KNOW RIGHT?? Irks me everytime I see it, I’m like “so? What are you trying to say? It’s just someone doing the same thing during different episode, it doesn’t mean anything.

It’s just not even the right word, honestly. Most times when it’s used the people using it are talking about themes, motifs, and symbols.
And like, they don’t have to mean anything. A motif can just be a repeated image or theme but whether or not it actually “means anything” is dependant on the context.
Dean wearing protective goggles in a lot of episodes is not a “parallel” it’s just Dean wearing goggles when he should be (using heavy machinery or doing things that could damage his eyes).
Character mirrors reflect and show us (or the character) something about the character we may or may not have noticed before. (But parallel and mirror are often used as synonyms.) Parallels should display every similar character traits and choices throughout and say something about each other.
Idk, friend, I have so many issues with the way certain terms are used. It frustrates me. I’m not trying to shade or be nit-picky, but half the time I have no idea what’s going on b/c terms.