It was always like that, this isn’t new. I usually keep a version and at the end I go through two major upgrades. So it’s every 9 month and in between just minor upgrades. I you jump on the first relase, you could like this even do 12 month intervals.
Currently, there are 2-3 versions maintained. 2 years means that there are up to 6 to be maintained. So every bug fix needs to be backported and tested to twice as much versions.
There were also discussions about LTE releases, but that makes the update procedures a bit more complicated (skipping major releases etc.).