The Open Signal data is devastating for 5G. The companies claim over 90% coverage. More than 10,000 participated in Open Signal's 5G tests in May. They only connected to 5G ~15% of the time. The only explanation I can think of is that the indoor performance of Korea's 5G mid-band is awful and much worse than I and many others expected. (Left and below)

I've been asking anyone with data for indoor figures but only getting anecdotes. What I was told was that the mid-band 5G had decent indoor coverage. I should have been much more skeptical in the absence of data. Better phone antennas, improved software for MIMO, and other technologies are coming. 

But if this data proves out, 5G offers much less than almost everyone except Dean Bubley expected.

When the phones connected with 5G, the average speed was over 200 Mbps.

Here's the availability chart full size