Almost always seen in the compound 秩序 ('order, sequence'). The standalone 'decade' sense (one 秩 = ten years of age) survives only in formal birthday language like 七秩寿辰 ('70th birthday').
The grain radical on the left ties the character to harvested crops being stacked up in regular layers; from 'piling grain in order' came the abstract meaning of orderly arrangement and ranked salary (officials were once paid in grain).
