Does sticking mindmaps on walls actually help?

it depends on what you find is most effective for memorising information. if you're a visual learner, absolutely go all out with mindmaps and plaster them on your walls (obviously within reason). if the process of actually making the mindmap is how you retained information, rather than reading the information off it, id recommend to just freely blurt out the information and focus more on active recall rather than glitzy notes and wasted blu tack. for sciences specifically, i found that watching videos explaining topics in detail, followed by active recall and then past papers was best for retaining information. make sure not to do all past papers available as they're precious resources closer to the actual thing, and for the ones you do ensure youre noting what you got wrong and going back and putting more time into those topics