all this proves is that it uses chakra.Body Flicker Technique (瞬身の術, Shunshin no Jutsu)
Ninjutsu, D-rank, Supplementary
Users: Gaara, Hatake Kakashi, et al
A movement technique with extreme speed like a gust of wind!!
Appearing along with the wind, disappearing like the wind: the ninja's instantaneous movement technique. This super fast movement is almost impossible to grasp with the naked eye. If seen by an ordinary person, it would seem as if the user has teleported... In reality, the user has vitalized his body with chakra and moved at super speeds. The amount of chakra used up differs depending on the distance and elevation of their stopping point in comparison to the starting point.
The cloud of sand dances in the wind
[picture of Gaara using the Body Flicker]
[picture of Haku using the Body Flicker]
[picture of Kakashi using the Body Flicker]
↑→Haku's and Kakashi's Body Flicker. Dancing leaves and disappearing in an instant like mist. There are many variations of the "Body Flicker" for the various villages and user. Gaara's use includes the "Sand Body Flicker"*. There are also the "Mist Body Flicker"**, "Water Body Flicker"***, and "Leaf Body Flicker"****, among many others.
*Sand Body Flicker (砂瞬身, Suna Shunshin)
**Mist Body Flicker" (霧瞬身, Kiri Shunshin)
***Water Body Flicker" (水瞬身, Mizu Shunshin)
****"Leaf Body Flicker" (木ノ葉瞬身, Konoha Shunshin
It doesn't prove that it makes you faster if you already hit your top speed. By this logic, those with larger chakra reserves should be faster by default.