The site is often very quiet indeed, close to 'dead' even, from around 3 am to 9 am UK time. This is about the period during which most members in the USA (who probably comprise the great majority of the membership) will have gone to bed. But actually, I think things are somewhat livelier now in general than they were a year or two ago.
One section which has become a bit disappointing, speaking personally, is 'Computers, Math, Science & Technology'. You sometimes see it go 24 hours without a single new post. There was a time a few years ago when threads about computing accounted for around half the posts in the section, but that seems to have dwindled to more like 10-20 percent of the posts. There used to be a lot more very knowledgeable computing experts taking part, such as Edenthiel. mr_bigmouth_502, Fogman, etc, but I haven't seen posts from any of these for ages.
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On a mountain range
I'm Doctor Strange