I've only done a handful of small lot land appraisals because there are just so few in my area. But there are a lot of large, rural or even remote tracts and that's usually what I end up appraising. The problem is that a lot of time passes between sales of what might be considered reasonably comparable properties. By the time you wrestle with differences in zoning versus lot size versus access, water, power, views, locations, different types of buyers, impossible to track down REALTORS, faulty MLS data, faulty public record data, certificates of compliance (which increase or decrease the potential for lot splits), retired APN's, new APN's, boundary line adjustments before, during and after the transaction and compound all this with the moving target of roller coaster ups and downs in the market over the years which is not the same from area to area, I usually end up with an unreconcilable bottom line.
So I try to solve the problem by discussing the price per acre range from low to high and how the subject property fits into the range (most like the these property, less like those properties, etc). When I'm "comfortable" with a PPA I just apply it the subject's lot size.