I think that this goes to reinforce that like home assistant you need to read the docs for the core component as well as the component itself. For example in esphome you need to read Display Core as well as the individual Display component.
Similarly in Home Assistant you need to read, say, the media player generic instructions as well as, say the squeezebox integration doc.
True 
With such powerful tools you need to RTFM or you are lost 
4 Gb memory dedicated to the HA VM.
I am just relaying my experiences. Maybe it’s something I have misconfigured - I dunno. I have another ESP8266 indication status with red and green LED’s, using the binary sensor from HA - works fine, so I know reading a sensor from HA works. But the example - as provided - cannot connect to WiFi it would seem. Tried on 3 different ESP8266’s. I did see posts about “Auth failed” messages and that setting the I2C “priority” (IIRC) to -100 helped for some people, but not me. Changing the I2C frequency to 200kHz fixed that issue. Just bad luck I guess!
There are a lot of posts on the forum that compiling an esphome project can run out of RAM on a pi. More likely to arise on a 512M or 1G RAM model. Compiling and linking is quite RAM intensive.
Thanks for the reply…
I asked on discord and the response was that the “update_interval” was how often ESPHome would read the sensor… Not specifically how often it would post to HA… But maybe that is implied.
I did use the search feature first but all it really does is find “throttle” in all the example code so becomes kinda unusable.
I’m confident that I can break something.
When it has data, it will post.
I questioned “4G” because I couldn’t quite grok what a cellular communications protocol has to do with ESPHome.
That’s very weird. When I search for “throttle” the very first result is the link to the sensor component documentation which I just posted:
Do your search results really differ @TommySharpNZ ? I can’t really imagen this…
So you had troubles in the past with the native API? I’m quite interested what this could be actually.
I have (too) many years experience with mqtt and also with the esphome native api.
When I try to compare both in my head the first things with come to my mind with mqtt is hours and hours of debugging, troubleshooting and doctoring on the mqtt broker.
The native api on the other hand just worked straight away the first time I touched it and does so till today. Not one minute wasted 
I just want to thank everyone for their replies! Good to hear others have had better success with the exact cookbook example I am having problems with - most likely something about my installation is causing the issues.
I’ll try the Debug mode, watching the logs just shows that the sensors connect (or appear to), but that’s it. My other nodes show traffic/data being gathered and passing - same settings.
Apologies… I obviously started off searching for “update_interval” and this is the one that brings up loads of hits from the examples.
You are correct that a search for “throttle” does bring up a more concise list.