I have a half dozen Apple Watch S0 in my family. Not a single one, not one, recorded heart rate while walking, running, cycling WITHOUT a work out running.
The reason why you see 1-3 minute intervals is the watch is detecting movement so it quickly takes a new reading because its assuming you won't be still anymore. This was added in watchOS 3.0, and was not part of watchOS 1.0-2.x.
At this point I cannot help you anymore. I have provided multiple sources and others have mentioned the same exact thing. What you are experiencing is not the rule, but an exception. No matter what I say won't change the fact that you experienced something you should not have experienced. So there is no point for me to keep repeating myself.
I want you to show proof that you actually had your heart rate recorded during various exercises while not running a workout in watchOS 3.x.x. I don't know how you could do that, but until I see proof that multiple watches exhibited this not intended behavior, its hard for me to believe it when I have 6 watches in my household that have never once done that.
Thanks.
All your sources are either old or third party, not Apple. I haven't seen once reliable source from Apple confirming this. So, I had a look myself. Contact Apple? sure, speak to a support guy who will confirm anything you say so you hang up!
Here is the HR information direct from Apple (and the most accurate so far): via
http://web.archive.org/web/20150415000000*/https://support.apple.com/en-gb/HT204666
2015
Apple Watch attempts to measure your heart rate every 10 minutes, but won't record it when you're in motion or your arm is moving. (every 10 mins).
2016
Apple Watch only takes this background reading when you're still, the time between these measurements will vary. (no mention of time, so assuming periodically).
2017
Apple Watch measures your heart rate throughout the day when you’re still, and periodically when you’re walking (Apple Watch Series 1 or later) (again, no mention of time).
As mentioned previously, it didn't act like this in WatchOS3 and it was reported to Apple. I am guessing I am not the only owner of an S0 that worked this way (my friends) and those other S0's out there. Strange that the S1 and above now act like my S0 used to. Apple obviously changed functionality but we can't prove or disprove that. You have a household with AW out of millions sold and the same for me.
So far you said and I quote:
5 or 15 mins?
"For the third time, it records every 5 minutes if you are STILL"
"Exactly the same. Once ever 5-15 minutes depending on if I was moving or not"
5x battery life?
"Oh and no where did I make any claim about battery life except that my S3 is 5x better than my S0"
"My S3 battery life lasts 5x longer than my S0"
my point exactly
"Just because YOUR S0 lasts 2 days doesn't mean anyone else's does."
exactly, just because your apple watch didn't record any HR during movement (which mine did as shown by my heath screenshots) doesn't mean that anyone else's does
"Not a single one, not one, recorded heart rate while walking, running, cycling WITHOUT a work out running."
That's it then, you have the watches used by Apple as THE benchmark for how they should function. Unfortunately, mine and my friends AW worked in a different way and it got reported to Apple.
"until I see proof that multiple watches exhibited this not intended behavior, its hard for me to believe it"
Yes, I am making it all up! ? Seriously, I used an AW Sports and it recorded my HR when cycling to work, SS S0, exactly the same. Same for walking and running. I only noticed after cycling to work after updating to WatchOS4 and thought, where's all my HR readings gone.