This makes no ******* sense and I wonder if people who made the calc read the chapter.
We see normal people, literal civilians, reacting to the blast and running away
as it is being fired. They are literally cities away from the blast and they're all reacting to it in shock and horror.
It has to have been several seconds at least to allow people to react like that.
We also see speedlines and a sweeping curve on the beam indicating that Psykos held the beam and swung it like a razor after firing it. Meaning it wasn't one-shot.
I was the one who made the calc.
The first question is...
where are the heroes reacting to the blast? Now, Metal Bat vs Garou/EC was in S city, many hundreds of km away over mountain ranges, the superfight tournament was in City B (which is much closer to Z city but still presumably over 100 km away) and it's unclear where Garou vs the tanktop army, heavy kong vs marshal gorilla and the Blizzard group vs. DO-S took place. Logically, City B and City S are so far away from City Z that a view like this should only be possible from either within City Z, or a nearby town.
The simplest solution is to say that all the heroes are at the same hospital within eyesight (much less than 100km~) of Z city at a hospital either in a distant district or an outlying town. It's possible that Metal Bat may be somewhere else, which would explain his longer travel time, but the fact that he can see Psykorochi as if it were a nearby mountain makes it seem like his hospital is rather close to Z city. More importantly, the heroes we see reacting to the blast: Heavy Kong, Snek and Lightning Max are at the same hospital as TTM, Mumen, the Tanktoppers and the Blizzard Group. I think that this hospital is again, either in a further district of Z city or a town in Z city's borders because TTM states that the hospital will need more beds soon and we hear sirens in the distance. As we know, Z-city and outlying areas are being evacuated according to the newcast Metal Bat is watching, so this lines up pretty well.
Okay, so we get two reaction panels while the beam is process. 1) Genos reacting, King and Tareo being blown away, 2) Max, Kong and Snek reacting to the beam flash, while civilians are running away. Let's break this down from the 1 second end perspective:
1) Genos can react to this, he's sub-rel at this point according to our profiles. 1 second is enough time for King and Tareo to start freaking out as the shockwaves blow them away
2) Max, Snek and Kong all have supersonic reflexes- they don't need a second, let only 60, to react to a bright explosion happening 15-25 km in front of them. Here's the kicker though: the civilians are running away because of the evacuation order in chapter 132, not because of the blast. Because it's happening in the span of one-second, they don't really have time to process, we see them turning their heads but no faces of knowing "shock and horror".
So...
1. the civilians don't have time to react, they're running because of the evacuation order
2. That's because all the people shown, civilians and hero trio included, are within viewing distance of Z city, if not within the city itself since it is so huge. They are not "literal cities away"
3. I understand that if Psykorochi were swinging the beam over the course of a minute or 30 seconds, it wouldn't be a one-shot, but if she's swinging all the energy in 1 second then it's all the same for our purposes of course.
I hope that you can see, when I made my judgment about the time frame, that I wasn't pulling it out of my butt. I tried my best to rationalize the positions of all relevant characters, what they were doing before the blast and their reaction times. All that considered, I determined the time frame shouldn't be much more than human reaction time- we have two small reaction panels with limited reactions and then the beam results are shown immediately after that.
Are we to expect that 10 seconds, or a minute has passed since then? Was Tatsumaki moving in a straight line with the beam for 10, 30, 60 seconds? Shouldn't she have tried to dodge in a more irregular pattern if she had such a long time to think of something? Shouldn't the beam cut have more been a chaotic twirl and Tatsumaki flew round and round attempting to get out of the beam? Why do we see Tatsumaki and Genos's thoughts after the beam, after the crust falls? According to this timeline, they must have taken a solid minute or two to ask themselves "where did all this power come from" or "it's immeasurably strong!" Those sound like more immediate reactions to me, taken a few seconds after a traumatic event.