I'm so confused. Does PurePulse mean continuous heartrate monitoring or not?

[monsieurpooh]

I'm looking for a device which can monitor heart rate without breaks (not just "sampling" every once in a while). I saw that Fitbit's PurePulse seems to claim to do this, which is something that Apple and Google's watches apparently cannot do (due to lacking in battery life). 

So naturally I'm confused why fitbit is the only company in the world who has this technology. 

Imagine my surprise, when I asked the internet why this is, and people are denying that such technology exists.  

https://www.reddit.com/r/AndroidWear/comments/buaemk/is_there_no_android_wear_device_capable_of/

Please clear my confusion once and for all: Does PurePulse mean actual ALWAYS-ON continuous heart rate monitoring, over a whole day? As in, without replacing the battery with no breaks in between, one could in theory write an app that saves the entire heart rate data of a whole day into a big chart, with every single beat shown (not just as samples every 5 minutes)?

If not, then how frequent is each sample (for example, does it take a 5-second heart rate sample every 60 seconds)?

If yes, then why isn't it widely adopted by the other big wearable companies? 

[SteveH]

My understanding is that fitbits using PurePule normally sample the heart rate every 5 seconds. When using exercise tracking this is increased to every second.