One Has to Wonder

What is it with me and taking forever to get interested in a show? Every single show I've ever loved I always got into about a season or two or many later. The only shows I got into from the start were Numbers and CSI New York and both shows I ended up losing interest in seasons later. I got into season one of Suits but, though I like the show, I have to admit it also pushes a lot of do-not-want buttons along with my like buttons, so it remains to be seen if it's the exception. But with the shows I absolutely love it's always been the opposite. SGA - got into it around season two. White Collar - the same. Dr. Who - the same. Even shows I like instead of love, like the Mentalist, I got into seasons down the line. Now I find myself getting pulled into Merlin after watching the most recent season (which was, what, season four, five? Yeesh! Took me long enough :P)

And I really don't get why this is. Anyone else find themselves getting into shows only after the fact that they've been airing for at least a season? Any theories as to why this is?