If you want to try, try. If you feel accomplished and satisfied with marks then go ahead. It depends on what type of person you are so don't worry about people saying its shit.
Im glad i tried and did well because im applying for ADFA at the moment, they took my SC and looked favourably upon it. Try your hardest so in the future if you decide to do something where they will look at your SC you don't look back and think, shit, maybe i shouldn't of listened to those people.