The time limit for the section II is one hour. You therefore have to write 2 essays in 30 minutes each which is quite a tough thing to do. This takes timing and organization and is one of the issues that most people struggle with. Within this timeframe you must write an introduction, a decent argument and a good conclusion drawing the threads together and re-iterating the main points. I strongly suggest that you spend some time practicing writing 30 minute essays, ensuring that you get all the necessary sections in.