In my view Break is just a way to reset your mind
If you are tired and dont want to play then you will face mind block, shit missing, frustration, not focusing and other things which will make you less consistent. This happens when you play daily just so you can improve.
When I was 13 I show many of my cusions playing PUBGM and I wanted to play it too but I didnt had any device to play on it. When I hit 15 I got a mobile and I used to play PubgM for 5 hours a day but as the time passed I got bored of it because I can play whenever I want.
This applied to osu too, When you start playing Osu, its fun and you want to be better and improve 'x' thing but the game become boring with the more time you invest in it, you start facing many problems like i mentioned on top. By taking breaks you can developed the same feeling when you start playing the game or at least somewhat closer to that.
But if you dont have any of these problem then break will do nothing
edit: also another thing "Mindset"
Did you ever had that feeling where you get a very good play and after that your whole session go very good
That happen because of your mind, If you made a mindset where you just think that you are bad and you cant fc anything then your whole session will go bad no matter how much you practice.
Develop a good mindset. Thats why many player say "Enjoy the game"