Where I'm at, our least dense zone is 1 unit per 2.5 acres. If the lot was almost, but not quite 5 acres, it couldn't be split without a variance.
In theory, the state requires the city to allow for 2x population growth, and the zoning process directs where the growth should happen. In practice, the city pushes back so hard on everything, that the growth is going to happen wherever whoever has patience and money to spend on fighting the council wants to build. Everyone else is going to be frustrated by the long process of back and forth on pulling permits over many years and many dollars that actually the city won't let you do whatever you wanted to do anyway.
