One of many things that I love about True Detective is the fact that there is zero filler; no unnecessary side plots to kill time; not a single wasted scene nor moment during you consider hitting the fast forward, so to speak. For me, this is what makes some shows great: a single-minded focus and determination on the writers' part to ensure every scene cleaves to the central theme.
Breaking Bad, despite some other faults, excelled in this regard. Everything was about Walt, and to a lesser extent, Jesse, whose character existed as a foil to Walt. The Wire, through its decentralized structure, was also able to achieve this; every plot strand adding to the tapestry that David Simon was weaving (except perhaps in the final season, during which I felt the newsroom story was a bit superfluous.)
The two biggest offenders are, by far, Dexter and Homeland. Witness the story line with Mazuka's daughter. I mean, what the hell was the point of that? Or how about Brody's daughter and her boyfriend in the last season of Homeland? Filler of the worst kind! The Sopranos fell into this trap during its last season, boring us with the Vito subplot. Game of Thrones (admittedly constricted by following a popular book,) veers close to this dangerous territory with the Sam Tarley subplot. Another show which I felt was badly affected by this was Deadwood. Why would I have any interest in Calamity Jane and the elementary school (run by Skylar White,) when this takes very minutes away from Swearengen and his gang? The Shield, an excellent show by and large, had a few moments involving Wyms and Dutch that felt unnecessary. All in all, moments like these in otherwise very good shows are bit like watching Chris Smalling at RB: what is the point of incorporating something that so clearly doesn't work?
I guess one thing to take away from this is that it's very hard to keep focus, particularly over a run of multiple seasons (again kudos to Vince Gilligan for managing this.) Perhaps that's why this mini-series format that True Detective is using is so refreshing. There's little chance of filler, given that there are only 9 episodes to get the story told.