Warp speeds in TOS never made sense, anyway. Neither did warp speeds in any other incarnation on screen, whether TAS, TNG, DS9, VOY, ENT, or any of the films. That is to say, every incarnation had examples of travel times at stated warp speeds, that were, even in the most favorable light, eyebrow raising.
Even the formula given in The Making of Star Trek
was totally bogus. According to it, at warp 8 it would take 3 days just to go from Earth to Alpha Centauri
, a ridiculously long time by Star Trek
has never placed consistency above all other factors. Why should it be held to that standard now?