i do not recommend you go in with "pre-planned time" restrictions, as this will most likely back-fire in your face! depending on each exam and the level of detail in each question, the time spent will vary from year to year. i encourage you all to therefore spend however long you need to on multiple choice and short answers, because remember, it is easier to pick up marks in short answers and multiple choice question than it is in essays. however, generally, the best students will spend about 10-15 minutes on multi choice, 40-45 on short answers and then about 1 hour on both reports. re-checking time is rarely there for the best students, as they are basically writing up to the last second. i know in my case i was writing until they said pens down! and my time allocation was what I said above, I think it was 12 minutes multiple choice, 45 for short answers, and then the remaining time for the scenario and section 4/case study response! and remember too that under exam conditions things become that whole lot harder.
good luck!!