The Sprint Action gives you 15 m, plus one meter for every hit on an Athletics + Agility Test; Most Street Samurai will easily get one or more hits.
By way of comparison, Usain Bolt’s personal best time in the 100 m dash is 9.58 second. That’s 10.4 meters per second... By the man who is literally the best person in all of recorded history at running very fast.
Given that Bolt isn’t being shot at, isn’t wearing body armor, isn’t carrying a katana in one hand and a submachine gun in the other... and is clearly using every last point of Edge he has when he makes his world record run. Yeah, this seems fair.
Since you brought it up ... i thought about this a few years ago when i had a short liaison with SR 5th Edition.
Looking at 5th Edition Usain Bolt would become much faster at running when he gets Wired Reflexes.
If he rolls 41 Initative he gets one pass each
at 41, at 31, at 21, at 11, at 1
so five Initative passes. In 5th Edition you could roll one sprint test each Initative pass and each hit gives 2 meters for humans. That would mean Usain Bolt gets like ~4 times faster at running just because his nerves and reflexes got superhumanly boosted … personally i think the 5th Edition run/sprint rules are terrible

But at least the base run rate was linked to Agility x4 which seems a good idea.
So lets look at the best non-augmented human possible 6th edition.
Agility 7 (with exceptional Attribute quality)
Athletics 13 (with Aptitude quality)
Edge 7
15 m + 27 dice means he runs between 16 meters/3 seconds and 42 meters /3 seconds
Thats 5,3m/s raising up to - depending on hits - 14m/s
And thats why other RPGs use fix sprint values. If you use the buy hits for 4 dice rules it gets less awkward. 15m+ (20:4) =20m/3s
Thats 6,6 m/s
A lot slower than Usain Bolt - but if i may take myself as example – a fix sprint speed is far more realistic than one day 3 m/s faster than at the next day or yesterday.