I don't know where to begin...
I am not
looking for T (Timeframe), the timeframe is resultant of other values, and not a factor for the calculation.
Claiming the speed which this fictional character can thrust a spear is variable is frivolous at best, and incongruent at worst. Yes, obviously the value is not set in stone, but we can use basic interpretation given by the work, the characters, and the setting of the world they're in to conclude plausible values to use in calculations. In this particular case, we are talking about a guy who runs an organization of assassins with Superhuman abilities, including strength and speed far beyond any natural human could ever achieve, still, his speed, despite being subpar when compared to even a casual Yor, still manages to surprise the much faster, supersonic assassin. It is fair to assume the guy also has some superhuman capacities, or at least above average.
The value does not come from thin air, my dear Den, no.
It comes from a scientific research which uses normal people as subjects for testing one-handed thrusting speed, with 12 meters per second being the best result amongst the normal person. Now, considering how far beyond humanity these characters are, how far beyond the human capacity this setting allows their characters to go, do you think the variables regarding the thrusting speed of this likely-to-be superhuman character could even fall behind a real life, normal person, with no training, spear thrusting speed? 12 meters per second does not act as a definitive factor for the character, or the calculation, no. It acts as the absolutely lowest point you can say this character could even go, based on interpretation, context, and the setting, all given to us by the narrative and the story.
You are actually under the strangest assumption that something needs to be said out loud in the manga for it to even be remotely usable. That is confirmation bias, and I am sorry to inform you, but you are incorrect.
In no way does our rules regarding calculations requires the manga to say the values to us directly. If your calculation is based on sound logic, and it is something that actually occurred in the particular media you're trying to calculate, plus, it has little to no contradictions, you are good to go. Furthermore, your petulant insistence on talking about this "favorite character" of yours leads me to believe you have a vendetta about some calculation about said character that was rejected, likely because there was an actual incoherent factor in it, and thus, you interpreted the reasoning behind said rejection in the most twisted way possible, and then began to spread said thought through other threads. But that is just a hypothesis of mine.
That is an interesting way to misuse a term, Den.
I will indulge you on this. I challenge you to define Calc Stacking to me, and make a logical "bridge" between this concept and my calculation. Connect the two for me, because not only me, but
@KLOL506 is struggling quite a lot to see said connection, at all. I really wish to read your reasoning behind such a claim.