Found this while playing with infinite jump Game Genie code described in https://tcrf.net/Jewel_Master

https://www.twitch.tv/shimegabriel/clip/SolidShyOpossumKeyboardCat-V-V2GSJcIrkKiUAQ

Best setup I've found is trying to jump as close to the end of the platform as possible, and perform the first jump with Speed Up + High Jump. After that you pause mid-air to switch to Double Jump for the second jump.

I try to jump when the character's feet are aligned with those bricks at the background.

This should make 10:5x more viable in the future.