Tbh, I would aim for more. On a normal a4 pad 3.5 but in the exam paper many 4.5-5. A beginning 4-5 paragraphs and the ending. At the end of the days it's quality though so if you have 2.5-3 very good context then stick with that. For me I'm weak with my content so I waffle for grammar marks
The examiner counts the words not the pages. You should write between 500-600 words as that's what you are expected. If you write less you will lose marks, if you write more you are at risk at making more mistakes.