@kenedyfake
I agree that characters who're around the same tier, tend to have comparable physical stats including speed stats. Exceptions would be if the mage has magic that specifically makes them faster (like Jellal, Racer, Jet etc); or if the mage is primarily a hax user (they tend to be quite low in all physical stats including speed. eg: brandish, neinhart etc)
But the concept of blitz, as far as I've understood, has little to do with defeating the opponent. It has more to do with attacking with speed which bypasses the opponent's comprehension or defence. A "win" isn't necessary to qualify an attack as blitz.
Eg: Racer was constantly blitzing Gray and Lyon, but he didn't win. Jellal blitzed Jura in GMG and Acnologia in Alverez arc (while he did basically no damage to Acno)
And, IMO, in speed, Laxus is superior to Natsu (no DF) and Erza. Especially if he transforms himself into lightning (he didn't do that in his fight against Erza if i remember correctly). It's just that Erza and Natsu has some unreal durability, because of which they can keep taking in punishment and still continue fighting.