It is definitely necessary, but the time for simulation should be considered. The difficulty of simulation questions is close to that of formal questions and simpler than that of training questions. If you do it first, it may make you feel that the exam is very difficult, thus ignoring the postgraduate entrance examination and some difficult problems, but it is also beneficial to do it first, so you will not be afraid of taking the postgraduate entrance examination for mathematics. I suggest that you can do it when reviewing the bottleneck and let education answer it for you.