I did higher edexcel maths and got an 8. for my exam board I remember a lot of questions about probability, algebra, triangles, circles. that being said, they basically covered all of the grade 7,8 and 9 topics and i'd say that the grade 1-4 stuff didn't come up as much, however the skills needed in the grade 1-4 topics were required to access the higher questions. I think its good to practice the grade 8/9 topics, but dont think that youll automatically get an 8 or 9 after practicing these as you might make silly mistakes on the easier topics. i'd recommend doing a practice paper and then highlighting the topics you lost marks on then practising these topics on maths genie.