What rapid time control is best for fastest improvement?

Comments? My highest rapid rating was 1212 as of May 30th 2022 I'm currently in a bit of a slum.......but besides that, I want to reach a rapid rating of at least 1400 for now. I am 38 years old. Has anything been said about chess improvement when it comes to rapid and the best time control, that should be set, for "fastest" rapid chess improvement? Thanks. And good luck in your games everybody

15|10 is the best time control online.
It is the official rapid time control like for World Championships.
It leaves enough time to play good chess.
Thanks to the increment you can always win a won position or draw a drawn position.

15|10 seems good yes.
But you also need to push your brain to fight against time. So alternate it with bullet or hyperbullet. And Chessable.

I like 10|0. My coach says that way you can practice actually being under a slight pressure of the clock sometimes, if you think very slowly.

The slower the better. But obviously not everyone has time for a 5h game a day...

10|0 has the best quality of games. The time control has the right time for you to think properly and has the right amount of time for you to be pressured.

I started playing 30|0 then moved onto 10|0 when I felt I my calculation speed was fast enough

I believe 15|10 is the best for improving, but I play 10|0 because I don't like waiting for my opponent.

You can try 15|10 and when you improve your calculating speed, you can do 10|0