Ram for the 9900x

Hi everyone, I’m looking for advice on which RAM to choose for my Ryzen 9 9900X. I’ve read on some forums that for stability reasons, it’s better to go with two sticks of CL30 RAM at 6000MHz. I just don't understand why cl30 is better than a lower number.

Can someone explain to me what does it mean? Is it even true, or can I go for faster models without compromising stability?

For the same price what's best? Cl28 cl30? 6000mhz or higher?

Any suggestions or experiences with optimal configurations for this processor are greatly appreciated!

Thanks in advance!