Trying to put Ichigo's speed that low for the sake of the calc is hiding an outlier.
Let's say that Ichigo's speed for the entire journey was Mach 1294, like you're assuming. That would make the distance 15179400 kilometers (about 39.5 times the distance between the Moon and the Earth), since his journey took him 9 and a half hours.
Things like Mimihagi, and Yhwach's Auswahlen are assumed to cross that same distance in about 3 to 5 seconds from what I recall. At five seconds, that puts Yhwach's Auswahlen at over 10 times the speed of light.
Who does this affect? Well, Liltotto for example, who before the distance calc was removed got her rating from dodging the Auswahlen, making her about 80% as fast as Auswahlen.
So approximately 8 times the speed of light for Liltotto and the other Sternritter girls. And this is just from assuming that True Shikai Ichigo's top speed is lightning speed...
You can't see why this is a little problematic?
This is why it would be way, way better in my view to just not bother with the distance calculation. It produces horrificly inflated results. No matter how you look at it, you end up with Liltotto being about 5403 times faster than True Shikai Ichigo's maximum speed.