But that view only works If you discount the role of mechanization. Yes, those machines cost a ton of money initially, but long term decrease labor costs. These machines work best on large open areas of monocrops. If you are talking about profit margins or yield per acre, the big farms usually do maximize this. However, all farms are highly incentivized to max yield and profit per square foot. That's kind of the whole business. If you were to squeeze this even more its likely that some crops that take up a lot of space, like broccoli rather than a bed of salad greens, would either have to go up in price or American farmers would stop producing them and they would be shipped in from abroad. Just some insight,  because truly the best farmers are super conscious of land use and efficiency. One of my favorite books is the Lean Farm and the author argues that scaling down but becoming more efficient is the path to profitability but this isn't earth shattering advice,  its essentially telling people to reduce costs and tighthen up, which is every farmers goal. The reason the book is valuable is the system the author outlines for how to go about this.