OK, even if we make it the minimum: 50 meters, the steps, 6 people knocked out - all in a flash before any of them move, basically a muscle. He's in one place, he's then a long way away before any of them have the chance to lift their hands. That's a decent enough feat, and it's not like it was remotely implied that he had to go all out to achieve it. He's casual (despite knowing that he has seconds left of OFA before transforming).
Whether it's dust or afterimage, the fact remains that he is on one side of them, then he's on the other, precisely picking up three other people while already carrying one, and they are still staring at the place he's at. He goes further away, and they still havent managed to turn their heads. Again, not done in "I'm having to go all out to do this." At that point, All Might still thought that he was going to one-shot the Nomu.
As stated above, it doesn't matter, given that he did all of that before they could move a muscle.
Again, he did this before they could move. He'd passed them, done some precise stuff, and they hadn't reacted even slightly.
I'm not really arguing that. What we have, though, is:
1. We know that OFA provides some degree of superhuman speed. We've seen it a bunch of times.
2. In a stroke of luck, as far as calc stuff goes, we know that Deku, thanks to Fa Jin, is using OFA at 100% when he literally outruns a bullet that is most definitely at least mach 3, probably faster, based on what we know the shooter can do with those bullets, and performs complex actions as well, all at that speed. This tells us, if we accept the feat, that 100% OFA is multimach speedster level. That's blitz-fast on bullet timers, even multiple high end bullet timers. It's probably at least a factor of 10 faster than anything Danny Rand or Peter Parker can do on their best days.
3. We know that, again, thanks to the lucky precision of the narration in the book, Deku's normal level of OFA with no prep, no special work, just the stuff he can do all the time, is 45%.
4. Here is where it gets scale-y: I don't see how 45% of the stuff in bullet point 2 is somehow even comparable to people who are a factor of 10 or more slower than 100%. I'm not saying that he'll be able to use 100% OFA against these guys, at least not all of them, because it does require some prep and some futzing about. I'm saying that he doesn't need to against most of them, because 45% makes him a lot faster than they are.
I agree that it doesn't mean he can do it constantly. He needs Fa Jin up and running to make faux 100% But he doesn't need to be multimach to blitz these guys. Single mach will do it. His big issue is Danny, in the martial arts bit, because Danny can AoE him as long as he gets the chance, and he probably maybe will here?
With the KF team, I agree to some extent: I think it comes down to Danny, and the others giving Danny the time to get those AoE's off, slowing Deku, and then they dogpile him. He's got much better soak then any, but he still gets stunned and feels pain, and there are a lot of them. If this were the arena, I'd be leery on Deku winning any against the KF team. But here, it's a city, Deku has concealment, hovering, webs (blackwhip) and precog, plus they start 500m apart. They will need to find him in the smoke, don't have his mobility at all, and he's definitely going to be able to build up Fa Jin enough for one or two bursts before they can close. He can one-shot a number of these guys at faux 100%.