STM32H7 SRAM ECC or STL ram tests to achieve DC up above 90%?

[Ccl.1]

HI !

There is a functional safety program when uesd STM32H750, I notice this MCU have ECC in SRAM part,。 so , If I only used ECC function , can I get 90% DC rate? And why in STM32H7 STL lib still have RAM TESTS lib and not used ECC instead?

Thanks!