youre doing good. i have some improvement advice but its all from 6k as i like 6k alot.
1)
if you cant get an A rank on sightread, dont bother if you can A rank sightread then reaching S rank wont be too bad
2)
stop grinding at S rank* theres no point imo
3)
*except when improving acc for hitting more accurately, focus on getting 98% (i play on lazer so because of how 300s work its prob closwr to 99% for you take 98% with salt grains) and focus on MA and PA, on songs you can focus on accs like 98% and 99% then only MA and PA matter as anything not MA and PA is just a mistake and doesnt say about accuracy
4)
sleep for 8 hour or atleast as much as you physically can if you cant reach 8 hours i got a massive skill boos at 8 hour sleep but now i cant seem to do 8 hour sleeos
5)
if you cant improve acc when putting effort in, focus on improving acc on comfortable stuff idk how to explain it well in a short way. basically, lets say youre improving by trying new hard stuff and it doesnt work, try focus on easier songs with good pattern execution and sorta raise the skill level of what you can do wihout putting effort in to raise skill level of what you can do whilst putting effort in. hope it makes sense
6)
consider changing posture + trying wrist up/down try changing keybinds and how youre arms are when playing.
KEEP ARMS STRAIGHT MOSTLY PLEASE SHIFT KEYBOARD BACK IF WRISTS ARE BENT. FOREARM AND HAND ANGLE SHOULD BE BETWEEN 160° AND 180° SO YOU PERFORM BETTER AND DONT DESTROY HANDS. i never broke my hands or anything its jusy inpirtant. i also tried not leaning back in chair while playing but doing some sorta goofy ass sitting straight up (angle of upper arm and forearm gone from like 150°ish to 85°ish) and i found i played better. like me, you might just be able to play wrist up without practice
BONUS) my sorta "routine" type thing for improvement is to A rank something and play it every session atleast once until S rank. the A must be a sightread for me
BONUS 2: THE SEQUEL)
when warming up, play with acc in mind if you wanna focus sessions on fingering quickly and not accurately, then play easier fun songs as warm up and focus on getting a good MA and just getting better acc. playing with good acc means it improves playing patterns and just hitting accurately in general so in a break section in a hard song that accuracy and getting a gumbazumbazillion marvs can save your S rank
this is the advice i could think of that you dont often see, gl on clear dandan