Farming 6 by the end of spring is something I can pretty easily manage, so the first big blueberry/starfruit harvest usually gets me 9 or very close to it by late summer.
the elite players can get Farming 9 in spring, but i just don't have the stubbornness to handwater that much Kale. It's a game, games are supposed to be fun, and I have more fun running around mining, chopping trees, and sating Maru's infinite demand for strawberries.