I wonder do any of you actually know how the

Watch works? This should have been reported a long time ago, even before the watch was launched.
If you read the
Apple Watch Programming Guide (i'm surprised that the staff on Macrumors didn't) you'll notice the figure bellow which explains how the apps are actually executed (and where).
Image
The UI elements are kept on the watch while the code and processing is done on the phone. The dashed blue line is the bluetooth connection.
Image
This is why there is lag on the watch when browsing through pages or clicking buttons: for every UI interaction, the watch "talks" to the phone and waits until the phone "responds". This is a very inefficient way to run apps, but at least it conserves the watch's battery, while draining the phone's. So even if your phone is in your pocket and you're not using it, it isn't idle, it runs apps for the watch, and constantly responding to every interaction the user makes on the watch.
The bottom line is that if you're using apps on the watch, especially non native ones (which i'm sure run in a different way), your phone battery is expected to be way lower.
Read more about this, here:
https://developer.apple.com/library...p.html#//apple_ref/doc/uid/TP40014969-CH3-SW1
There are a few things you should consider in your analysis:
- WK extensions running on a phone don't need to power the phone's display. How significant is that, do you think?
- WK extensions running on the phone don't render the Watch UI -- that happens on the watch itself. (In many kinds of mobile apps, the processing to render the UI dwarfs all other processing).
Considering the limitations of the WK API and the nature of the Watch, what high-power activities are there that really make sense for the extension that runs on the phone to do?
An extension mainly reads data, adjusts a small UI consisting of a fixed set of preexisting elements on the watch based on that data, and perhaps writes some data. The amount of data is typically going to be very small -- this is for display on a 1.3-1.5" screen. So I don't see the processor, radios, sensors or storage system working hard, typically.
Now, I'm sure it's possible to write inefficient WK apps that drain the phone's battery. But I don't see anything inherent in the architecture of WK that makes that inevitable. In fact, it looks like it makes it easy to be efficient.
I'd be interested in seeing data from actual power usage profiling before drawing conclusions about the impact of WK apps on phone battery life. Just considering what we know from analyzing the SDK I'd expect it to be pretty small.
----------
Still awaiting on my Apple Watch but could someone explain to me why you would leave the companion app opened? Does the Watch need it to run in any fashion? I was under the impression the Companion App was used to make changes to settings, apps, etc. no reason to leave it opened processing in the background unless you simply forget to quit it. Am I correct in saying this?
On iPhone, you don't need to close or quit apps to have them stop using power. It happens automatically.
My advice to you is don't listen to random people's anecdote-fueled theories about battery life. Most of them are complete hogwash.
Instead, use your phone and watch in the most useful and convenient way for your own needs. Do that for a week or so. If you end up having no problems with battery life then, great! The Watch and phone are doing what you want and you didn't have to give up anything. And if you do end up having battery life issues, at least you'll have some good info that is relevant
to you rather than the random impressions from the internet, and you'll be a lot more likely to be able to find a workable solution.