Actually I'm not so sure about the sims. After taking my exam, my position is that you really need to be familiar with the AL so you can quickly find what you're looking for in it. I think it's important to practice some Simulations to get a feel for them. But after having taken the exam, I could have done a hundred more simulations and I don't think it would have prepared me for the ones on the actual exam.
All of my Simulations were on topics covered in the MCQ. So by really practicing the MCQ and knowing the concepts, you're preparing for the Simulations too. But the simulations were just a lot more complicated and difficult than I was expecting.