It wasn't that granular. Maybe a few blocks of the city in size, give or take. The visualizers I'm seeing have a single hexagon span the entirety of Austin, TX for reference. At least in Uber's usecase, that was less than useful.

It’s a hierarchy… so you can take your pick of granularity? Only thing that matters is min, max and step-size.

Unless we’re talking about different things, I’m not clear why we’re not assuming the tool you remember chose h10 or whatever level was actually useful to it, where the visualizations chose h5

I don't remember ours being a hierarchy but perhaps it was just the visualization.

Uber's internal stuff used resolution 9 i think...

That table shows H15 cells are on average 0.9 m^2, or a hexagon with edges 0.59m long.

(The average edge length is 0.5m, but that's not the same as the edge length of the average area hexagon)