Your friend may google CT Real Estate Tax Assessments and get the CT law for how each town is supposed to do it. Reprinted is a subsection that may be informative:
(b) (1) Commencing October 1, 2006, each town shall implement a revaluation not later than the first day of October that follows, by five years, the October first assessment date on which the town’s previous revaluation became effective, provided, a town that opted to defer a revaluation, pursuant to section 12-62l, shall implement a revaluation not later than the first day of October that follows, by five years, the October first assessment date on which the town’s deferred revaluation became effective. The town shall use assessments derived from each such revaluation for the purpose of levying property taxes for the assessment year in which such revaluation is effective and for each assessment year that follows until the ensuing revaluation becomes effective.
(2) When conducting a revaluation, an assessor shall use generally accepted mass appraisal methods which may include, but need not be limited to, the market sales comparison approach to value, the cost approach to value and the income approach to value. Prior to the completion of each revaluation, the assessor shall conduct a field review. Except in a town that has a single assessor, the members of the board of assessors shall approve, by majority vote, all valuations established for a revaluation.
(3) An assessor, member of an assessor’s staff or person designated by an assessor may, at any time, fully inspect any parcel of improved real property in order to ascertain or verify the accuracy of data listed on the assessor’s property record for such parcel. Except as provided in subdivision (4) of this subsection, the assessor shall fully inspect each such parcel once in every ten assessment years, provided, if the full inspection of any such parcel occurred in an assessment year preceding that commencing October 1, 1996, the assessor shall fully inspect such parcel not later than the first day of October of 2009, and shall thereafter fully inspect such parcel in accordance with this section. Nothing in this subsection shall require the assessor to fully inspect all of a town’s improved real property parcels in the same assessment year and in no case shall an assessor be required to fully inspect any such parcel more than once during every ten assessment years.