If a show is widely loved in its 1st season, it will be hated by the 7th.
The reverse holds true, if hated in season 1 and it makes it to a 7th season, it will be widely loved by its 7th.
If the show is a spinoff of a popular fictional franchise, expect the above rules to apply tenfold.
I'm thinking about calling this Hurley's Rule. Or maybe the Lost Rule (it doesn't have to be 7 seasons for the rule to work, as it's usually going to apply with anything running 5 or more seasons)--or the TNG Rule, in the case of franchise spinoff series.
Regardless of whether a long-running series begins loved or hated, it is often the 4th season (sometimes the 3rd; generally speaking the peak usually comes around the early to halfway point of a series' life--writers and producers have gotten into a good routine and understanding of the characters, but there are still a lot of fresh ideas and arcs to explore before they reach the bottom of the barrel) which exists as the fulcrum point, or the "peak". Everything before or after will always be compared to the peak (even the shows that went from hated to loved will usually be measured up against that peak season--"It's great but season 4 was the peak"), and that point in the series will either be regarded as the point where the show "got really good" or "jumped the shark". See also the TV Trope "Growing the Beard'
Despite some hiccups in seasons 5 and 6, it really seemed to be season 7 of GoT where the fanbase started to turn and everyone started loving to hate GoT rather than loving it. And 4 is usually regarded as the best GoT season by miles. It's a prime example of Hurley's Rule. Many showrunners will know this and make efforts to wrap up their series by the 5th or 6th season (Breaking Bad, for example) in order to end "on a high note".
Dexter is also a perfect example. To a tee, with season 4 as the widely accepted "peak".
Could also think of it as the Hate for Love's Sake Rule.