Proper zoning for the type subdividing you have in mind is critical! Eighty percent of the counties in the US having zoning of some kind. Some people look at this as an advantage as it controls the amount and quality of the growth in an area, while others look at it as an infringement of their rights as owners. The counties have zones which are created by the planning or zoning commission and some of the basic zones are; residential, commercial, industrial, and agricultural, with each one having several categories of restrictions. There can be restrictions on the minimum number of acres per parcel that you can subdivide your property into, limits on the number, size, or purpose of buildings, number of homes and population density per acre, etc.
New zoning is not normally that much different from the type activities or zoning already in the place for a neighborhood. But there are stories of people who have owned their property for many years and suddenly are restricted as to hat they can do with it! And without compensation! Zoning laws for particular areas cause some problems but their absence can also. You may have a beautiful tract of land and unexpectedly have a paper mill built near you, or have mobile homes or very small houses appear nearby, or a stock car track! Who knows? Personally I prefer zoning restrictions as long as they aren't greatly restrictive. If you are involved in real estate, it is beneficial to stay informed of the present zoning laws and proposed changes, as well as other county activities, such as planning for new roads or industrial parks, etc.
Once zoning laws are in effect, the county building and health departments ensure they are abided by as they won't issue building or sewage permits until they have analyzed your proposed building or subdivision plans. Should you locate a parcel of land that you like but it has the wrong zoning for your plans, there is a possibility that you might get a particular zoning changed. Once I was successful in getting the zoning changed from residential to commercial on a large building lot my wife and I had acquired, which allowed us to sell it to a doctor for a new office. But it was a great deal of trouble and was certainly time consuming. After I submitted the request to the planning commission, we had to get signatures from property owners in the neighborhood stating that they didn't object to the zoning change, and present them to the commission. Once they received the signatures it still took forever as it had to be advertised and presented at a council meeting. But if finally worked. If a Realtor tells you that the zoning can be changed or a variance received on a particular property, I would be cautious as it is difficult, and sometimes impossible.