I don't like "During" because it indicates continued action--I'd use "in." Also, why the past perfect tense? I'd just say "i received." Also, there's too much passive voice going on. And as for "most seemed to be given arbitrarily," you have to reword or discard it. What do you mean here? It wasn't your fault that you were late? In that case it's not that the write-ups were arbtitrary, rather they were unjust/unfair. Or do you really mean that sometimes when you were late you were written up and sometimes not. I'd really like to know how this figures in to a statement.