I would not recommend memorising essays when preparing for Section IV. Unlike English, where students are able to memorise essays and make some changes to them to suit particular questions of an exam, in Business Studies, it is not possible to thoroughly prepare for Section IV by memorising essays. This is because there are numerous types of questions that could be asked, which can refer to different concepts (i.e. there is no guarantee that the essays that you memorised would be relevant to the questions that are asked in the exam). This also means that it is unrealistic to memorise a large number of essays in preparation for Section IV.
Instead, effectively preparing for Section IV starts by gaining thorough knowledge and understanding of the content across all topics, since a Section IV question can cover any of the four topics. Once you become confident with your knowledge and understanding of the content, you should attempt practice Section IV questions, allowing you to apply your knowledge and understanding of the content to exam-style questions. Subsequently, you can seek feedback on your responses and ensure that you address any areas of improvement that are identified, allowing for gradual improvement and, ultimately, favourable performance in Section IV.
I hope this helps!