Well not sure I do it as quickly as that, but I do answer many questions quite quickly with long detailed answers. In my case I’m a reasonably fast typist , not professional levels but not too bad - you need that of course, touch type, 60 wpm upwards. Also have been following my specialist topics for a long time, some of them since the 1960s. Read a lot. So - when you are familiar with the topic then it is much easier to remember things. So, I remember things I’ve read or heard in those areas.

So for instance in a question about tides - I already know that some parts of the world have one tide a day, some have two tides, some have more than two tides. Most people wouldn’t know that but that’s just because I’ve been interested in general science topics since my early teens, nearly half a century ago, and I find it interesting, so just remember things like that. It’s the sort of thing that once learnt, I probably won’t forget.

Also, I know roughly how the tides are created and so on. Also one of my sisters lives by the sea and when I stayed with her for a few months then I saw the tides continually changing and being mathematically inclined it was an incentive to find out all about how tides work. And that was just a few years back so reasonably fresh in my memory.

So then I know what to look for, but don’t have the citations to hand. So, it’s a case of googling, for instance in a google images search for a map of the parts of the world with the different types of tides, I found this very useful map:

Here the places with diurnal tides - so just one tide a day - are marked in yellow. The ones with two high tides a day are marked with red coastlines, and others shown in blue have mixed tides somewhere between the two. See NOAA's National Ocean Service: Low tid

That often then leads me to pages written by experts, papers in google scholar, NOAA in this case pages and so on . So I can read those and summarize what they say. I’m a fast reader which helps. Then I find wikipedia useful also. They often get some of the details wrong, but have lots of cites so I follow up the cites - and then sometimes correct the original articles if I find they made a mistake.

This is my tides answer; Why are tides caused by the Moon rather than the Sun?" Though just realized, reading it now, I never said anything about the interesting phenomenon of the double high tide at Southhampton, done it now. I don’t know how long it took, probably several hours. But much faster than if I hadn’t known that stuff already.

For other answers, there’s also copy / paste. Sometimes I can answer a question using a copy / paste of a section of a longer blog post on that topic. So sometimes I answer several answers quickly and they are mainly copy / paste with some editing.

Otherwise, well it’s more than an hour per answer for the long detailed ones. But I might edit it for quite a while when I publish it. So if you see several soon after each other, well it doesn’t include the amount of time spent on the first one (I think). The most important thing though is the accuracy. I did postgraduate research into maths / philosophy and learnt a lot in the process about how to identify reliable sources - what to look out for, how to tell what is accurate and what isn’t - even amongst published scientific papers there are low quality and high quality ones, so you get used to that, to being able to tell that.