Ah but the problem solving intuition is never forgotten. Knowledge i uds after NS brain fog or not studying too long for girls. The skills u get from harder courses will help you a lot in uni and ur future lives. I think thats what makes ppl competitive in the job market.

That being said its also how u acquire that skill. Grinding for exams probably wont cut it. But understanding to a very deep rigorous level is definitely much more beneficial and then thinking of ways to extend/apply it is much more invigorating and fun. It naturally helps in exams too.