Why does it seem burning a BD-R at 10x seems smoother than 8x?

I have BDR-208DBK and using Verbatim 25GB 6X BD-R model 97457 discs and burning at 10x seems like it’s more smother of a burn seems to be less slows downs and speed ups and maybe less noisy. That due to the burner just not like burning at 8X but is ok and at 6x and 10x for some reason is smoother, is this normal and why ?

Different writespeeds are due to different strategies (firmware).
“smoother” doesnt mean better…