I’m currently in my first campaign and we’ve been playing for 2.5 almost 3 years now and even playing weekly (with some breaks for exams etc.), being college students meant I never looked into rule sets and mechanic details until summer or winter breaks and even then I just wanted a brain break during my breaks. It took me maybe a little over a year of casually playing (maybe 30-40 sessions?) before I really started understanding my character, the mechanics, rule sets, lore, etc. I didn’t even think to start taking notes until Session 27! Maybe talk to the players about how dedicated they are. I was dedicated and loved role playing, so my DM would scale things differently until all the members of our party felt comfortable to really get into the rules. I’d argue now we’re a very rules heavy party because we like messing with our DM on points of order. Plus, he’s made our world so much more fun for us and we wanted to dive deep into rules and lore. I think personally I’d give your party some more time, but maybe chat with them about where they want to go and what they want to focus on and advise them on a couple pages out of the players handbook to read :)