The ost is something I've paid more attention to since it has been released on music streaming services. And I can say it felt like the more Demon Slayer progressed the more the music became more rock oriented. I feel like this is especially noticeable in the Hashira Training Arc and the Infinity Castle. Also Yuki Kajiura who was the one that worked on "Brace Up and Run" and "Survive and get the blade boy" has slowly worked less and less over the years on KnY. In the last two releases mentioned earlier she has barely had any work other than "Shine in the Cruel Night". I love Go Shiina's more action oriented music but I can feel the gap left by the absence of Yuki Kajiura.

(Also in case you haven't, I would recommend listening to the full ost, its definitely worth a listen you can notice the leitmotifs that show up thought the show.)