Ok, so English exams are marked by 5 marks per PQE. But you can get extra marks for structure etc.. So for a 30 mark question i'd be quoting 5-6 times. Remember 30 mark questions are generally Studied fiction,poetry and drama , so you should have 6 quotes anyways.
Just a general tip, you should divide 5 into every question you get to see how many quotes and different ideas you need to talk about.
Good Luck in your exam!