I usually give a series 1-3 episodes chance to judge if it's worth the time. Agents of shield didn't grab me at first because I don't like watching detective/crime style series. The more it went on going, the more it turned into "fantasy" if that is the right word.
I'm quite picky on what to watch as with work, gaming and youtube you won't have time to do everything.
Depends what you are looking for of course.