SEF - Renovação do título de residência

Why does Sef have different policies for students? As known there are several strikes in Portugal in the past few months, some classmates of mine have been caught in this situation all the same. Then we asked the officers only to be told that we should make new appointments and that’s what I did, yet those who hadn’t made new appointments went back to sef and somehow they succeeded renewing their residence cards. How on earth do the students play by the rules don’t get to get the result they want and those who didn’t do? If sef has different policies towards different people, please let me know.