There's been much concern & controversy around hex density & the Transmit Scale assigned to each hotspot, and -- in my opinion -- it's been overstated, oversimplified, and misunderstood. I'm going to attempt to explain why I think so in this post. There are a lot of moving parts to consider here, so bear with me if things get a bit complicated.
The Helium network as a whole is purpose-built for primarily one thing: data transfer. We also need to understand and consider that Proof of Coverage exists first and foremost as an incentive mechanism to develop and grow the network; over time, the network reward structure will incrementally shift to data transfer as opposed to PoC rewards.
This is important context to consider whether you have a short or long view perspective. In the long term, it helps to understand that what should be emphasized is witnessing not being witnessed for optimal data transfer rewards. Put another way, it's more valuable to hear than to be heard. In the short term, this perspective helps you understand the network (including PoC) is optimizing for and rewarding according to the latter long term incentives -- why is this important even for short-term interest? Let's look at PoC rewards.
PoC carries a bias
Data transfer can be bi-directional (transmit/receive); however, MOST of the expected network traffic is relaying/routing received data [from IoT sensors, etc.], at least with the current "IoT" hotspots (5G is another story; you can read more about that directly from Helium CEO Amir Haleem here).
Having said that, the network economics value hotspots optimizing to best RECEIVE data [witnessing transmissions] over optimizing to best TRANSMIT data ["beaconing"] by 4x:
The entire PoC system is designed to both prove a check of authenticity (prove that you are where you say you are -- 1 through 3 in the above graphic) and as a "calibration" mechanism to incentivize the best placement (coverage area) and performance (data throughput -- 3 & 4 in the above graphic).
We've established that the data throughput is more valuable in the receiving direction than in the transmitting direction [for the purposes of IoT applications], and that it follows that witnessing other hotspots is more valuable than other hotspots witnessing you. This is where the Transmit Scale comes in.
Transmit Scale relates to beaconing
The Transmit Scale that you see for each hotspot on the Helium Explorer is only related to its own beacons -- #2 in the previous diagram above. This means the only time it comes into play are when the hotspot in question is challenged and transmits a beacon. this accounts for just 5% of the rewards available. What should really be more of an emphasis is what the Transmit Scales of the surrounding area hotspots are, and this is ultimately really out of an individual's control, outside of coordinated cluster placements.
For an even more in-depth understanding of the particular HIPs relating to hex density, check out the video below for an explanation direct from Helium:
Want to witness even more hotspots? Try an upgraded antenna! Install outdoors where possible, and as high up as you can manage -- the higher the better! #LineOfSight