contextually i think it's a pretty accurate seeing the speed boost tanjiro got when obtaining it, in season 3 once Tanjiro unlocks reawakens his mark he manages to blitz the three demons that he could barely fight even with Nezuko and Genya's help and manages to cut all their necks, moving several meters before any of them could dodge or move their arms up to blockThe 10x speed gap seems out of place to me, and the x10 multiplier seems out of thin air, but it was approved by the moderators.
he got so much faster post mark he even managed to sever sekido's in motion arm before it can reach Genya's neck to impale him with the staff even when it just was a couple inches away from doing so, he even managed to slash his neck in the process as apparent by the streak of blood we see