I'm considering one of these for my dc but it's a lot of money and I want to make sure I pick the right one. Just for context I think there are some gaps in dc's understanding in some areas (lack of effective practice and revision) but really needs repeated practice more than anything. dc uses all the free resources like math genie already which helps but I feel they need something extra and I'd like something where I can double check work is being done. Mocks were not good at all 😞. Has anyone used either starting from a low level? Thanks in advance for any insight.