In making the apportionment and assessment provided for in § 69-5-304, the lands receiving the greatest benefit shall be marked on scale of one hundred (100), and those benefited in a lesser degree shall be marked with such percentage of one hundred (100) as the benefit received bears in proportion to the scale of one hundred (100). This classification, when finally established, shall remain as a basis for all future assessments connected with the objects of the drainage or levee district, unless the county court, for good cause, shall authorize a revision of the classification.