I only got a 36, so take this with a grain of salt
I absolutely despised reading my entire life. I barely read anything from ages 5-15, even the compulsory books I wouldn't touch with a ten foot pole. I went my whole early highschool getting C's and D's in english, and the occasional B if I was lucky. When I was 16, I had absolutely no internet for a few hours and being bored out of my mind I picked up a book I bought 3 years ago from a bookshop that was just lying around. I read it, and I loved it. After that, I think I read over 60 books in year 10, just powered right through them.
When I came back to do year 11, I ended up getting A's and A+'s in english. I think by reading books I really loved and enjoyed, I was able to grasp concepts of knowing what to look for when thinking about certain characters, themes, ideas and coming to my own conclusions and opinions on certain books. I found myself asking "why do I hate/love that character?," "what was their motive," "why did the author kill off my favourite character?" etc.
I like to compare it to watching a movie, when you finish the movie, you might talk about for a while with the people you saw it with and discuss it in great detail, the parts you love, what part about the character makes you like/hate theme, what was the overarching theme/big picture of the movies etc. I think when you are reading something you enjoy, it can be easier to analysing that book than one that you don't like (typically most English books from school) and it can be an easier learning experience to get your skills up. I also found that by reading books for pleasure, my ability to write improved, as I liked how some sentences were started/ resonated with the writing style. My overall comprehension of media in all forms improved alot because I actually cared about it. It also gave me the power to push through boring English books lol.
I also don't think that if a book is hard or easy will make that much difference. Sure, some books with more complex themes may be more useful in the long run, but they don't have to be like that all the time.
I went into VCE hoping for a 30 in english, and I walked out with a 36. Not as inspirational as other storied with getting 40's, but I think if I didn't get into reading for pleasure, I wouldn't have gotten anywhere near that score. Hope this helps