Planning foe english???

Hi, I am doing the AQA English GCSE tomorrow morning and like always I worry about the amount of time given and I always feel like it isn't enough. I write quite a lot for each question and in the mock exams I got an A and in the controlled assessments my overall grade was an A. I have never really been the type to write down a plan and have always made mental notes on what I am going to write. The teachers always talk about actually planning your work but I just ignore what they say. My question is does planning really help to better your grade?

For Question 4, 5 and 6 I think planning is a good idea, otherwise it could end up just being a bit rambling and waffly. Particularly for Question 6 you want a plan because if you don't then you might not end up finishing properly and this could affect your marks as the ending might not match the form (e.g. letter, blog)!