I have a tough time of sitting through two hours of anything, even things I like, without needing a long break afterwards to do other things. At that rate, it would take me at least more than five years to watch every Trek episode, movie, and documentary. At the very minimum, it's about a thousand hours.
I'd also fear watching that much Trek back-to-back may not be good for my fandom, really...
Free your mind, and the rest will follow.