Netflix is one of the most proactive data-driven companies out there. Their insights department is on top of their game, using data to not only produce a finely-tuned recommendation engine, but also to steer the direction of new and original programming.
Frustratingly, Netflix does like to cancel seasons leaving fans (and subscribers) angry - take the recent nixing of Marvel shows including favorites Daredevil, Jessica Jones, and Luke Cage for example.
But why would Netflix cancel popular shows? Data.
The sweet spot for most series is 2-3 seasons before viewership dips. You see, a new series is where the real money is for the streaming behemoth. A new series creates buzz and excitement among a larger proportion of current subscribers and attracts non-subscribers, something which a legacy series doesn't do as effectively.
Data also informs Netflix about series length - and their model goes against the grain of broadcast networks. Netflix prefers ten episodes or less, whereas broadcast networks typically opt for seasons which are double the length. NBC and others don't necessarily have it wrong, but it's likely the binge-watching model plays a significant role in Netflix's decision. Ten episodes are far easier to binge than twenty-plus episodes.
So, don't stress when Netflix cans one of your favorite shows - there is hardcore data that shows you will move to a new series soon enough.