Don't be pressurised into taking more exams at any one sitting than you're happy with. The schools usually split the subjects 7:7 or 8:6, but that doesn't mean that you're obliged to take the exams grouped in that way. Choose the combination that's best for you. You have four attempts at each subject and six sittings, to be completed in 18 months, so spread them out a bit more, if you wish.