'best' is relative here; lower bands travel further, which is great for maximizing coverage footprint, but not great for high-density. Each node can only handle

'best' is relative here; lower bands travel further, which is great for maximizing coverage footprint, but not great for high-density. Each node can only handle so much traffic, and you can pack them in more densely with short-range spectrum. mmWave really is the best frequency for very high density, high capacity networks, but the bottleneck is you have to deploy all the extra nodes to get the coverage.