Every year ending in eight, no matter how large, whether Presidential or not, is an even year: 0 ... 8 ... 18 ... inifinity. You get the drift.
I could qualify it by stating it applies to presidential election years but that would make the title of this thread lengthier.
All the poor pollsters and both campaigns could have saved themselves the money and the time. And if I’m wrong - well then you’re right, we do have free will and rules are meant to be broken!
Our next one term President will be elected in 2028. So we will have a few two term Presidents until then. ;-)