Are you sure that's the case? I'm just speculating, but my gut feeling is that the timescales are more lax than this. I imagine the 1 tick window would apply to the actual generation of a speedshot, however to the best of my understanding, the firing window would be larger due to the variety of aiming that can be used (more speed, more height), and also as stated earlier that the ground can be 0-2 units above ground.
I'm pretty sure that's the case, although I really haven't looked into how many windows there are or how long they are but if I can manage to write up a script in python or something I can really look into it with actual in game data. Where you aim would have an effect for sure and would probably just move the window based on where you aim.
And that just means that there are at least two 1 tick windows, but including aim there's a chance for I'd say up to four 1 tick windows, BUT this is with no testing or anything.
For bounces it makes sense that there is a 1 tick window because any more and you'll get reset, but that's not the case with speedshots.
Except with speedshots your horizontal speed gets reset to the class' max walking velocity 1 tick after the window for the speedshot. So every window for a normal (non-prefire) speedshot is 1 tick.
If I'm even close to right thinking this, it could also be that pre-fire speedshots are simply like bounces with more speed/height, and would also explain why having more speed/height makes it harder to time a speedshot because the amount of viable shots that land on the right tick would be reduced.
Pretty much, speedshots are harder from higher up simply because the rocket needs to catch up to you and hit the ground at the same time, which is tricky when you don't stop accelerating downwards.
That said, like bounces you can speedshot going 3500u/s downwards, but the timing needs to be perfect.
And I really really want to try that now.