I watched ST in re-runs so many times I could tell which episode it was in about 5 seconds. I’d watch it just as much now if it was on. (Maybe I should get the DVDs).
I know that feeling with shows I’ve watched many, many times as well.
A while back they remastered the show and upgraded the effects shots while keeping intact the actor scenes so if you get a blu ray dvd set that is what you get. The original less than state of the art shots have been phasered out.