Ok, If you don't like your subject don't do it! I absolutely hate Ancient History and I'm dropping it immediately. The only bad thing is if you bomb out in one of your subjects then you don't have another subject to back up on... I'm willing to take the risk because I believe I'll be able to go really well in all my subjects anyways. Doing 10 units doesn't affect your ATAR but if you screw up in a subject that's when it'll affect it.