Under no circumstances should you compare assessments with other properties
Actually I had a book somewhere with tapes that described the process of using comparable appraised values. This tax consultant did nothing but tax appraisals in Cal. and NV. In Arkansas, this is one very good way to do it. In one subdivision of condo-duplexes, mostly with older folk living there, the entire subdivision was appraised based upon 1 sale, post-appraisal (sometime between Aug 31 and Jan 1, dated for Jan 1) three other sales occurred that were much less. Several neighbors got together and came as a group. The entire subdivision was lowered. Oh, sure. I heard board members query taxpayers what if we raised everyone else's rate but left yours the same...bullying tactic as i see it....taxpayers are neophytes to the machinations of the assessment process and should not be treated like that.
Also, I took a class with a Missouri tax consultant/appraiser who used that technique. He only appraised commercial properties and he actively sought over-valued properties, then approached the client with a proposition to lower the values. It works.
It sounds like your state has a system whereby assessment cannot be overturned with any sucess. The 5,000± complaintants in my home county in 1997? 91% were lowered....one property was raised (due to an error of 16,000 SF barn being logged as a 1,600 SF barn.)
In our state we contest the appraised value, not the assessment. State Constitution requires all ad valorom appraisals are "Market Value" appraisals. It is easy to see whether a property is over or under appraised. I did a spreadsheet of property I appraised for about 2 years comparing the assessor appraised value vs. the actual sales price of those properties that sold. It was 50%± to 150%± with the average being 105%±....The variance is unacceptable by almost any standard except the government. If the values had been 93% to 115%, It would be more palatable. At least you would think it fair. In fact, in Arkansas taxes cannot rise more than 5% per year regardless the assessed value, but that issue is entirely independent of the Appraised value.