GPS accuracy is really bad.

No, up to 90 hours with GNSS enabled (Best settings)- But can reach 280h with enough solar power.

With the lowest it's up to 500 hours.

The 280h is just the training mode without GNSS, so not applicable. And the 500h is power saving GNSS mode - there you have the UltraTrack and Expedition modes on Enduro 3 - 77 days (over 1800h) and up to unlimited with Solar. 

Enduro 3 Owner's Manual - Battery Information (garmin.com)

If you say so. Suunto says otherwise, but it's unimportant. Surf in to Suuntis website if you are curious.

But Suunto also has an extremely long battery life in the laboratory with constant access to solar energy. We all know that it is a sales ploy, just as much as a new car never reaches the promised range.

So better to accept that there are people who think the Enduro 3 has substandard precision in its GPS and therefore Garmin should fix it. 

That's how you create a large customer base by listening, not flatly defending your brand no matter what. No brand is perfect, and Garmin included.

My point 100%. Thank you. My Instincts and my partners Fr165 is better than E3 that's why I was so surprised with my results....

So add an alternative then with better GPS accuracy? I don't see the problem. Not that it's affecting the watch and it's durability..

Me myself don't care so much about it. Not often I need it to be so precisely, but it happens and then it would be nice to have that ability to chose what fits my need right now.

Even if I finds it rather funny that my watch for 1000 $ have a hard time with GPS accuracy meanwhile my other watch get it perfectly.

trux said:

How long does it last without charging? The main goal of Enduro 3 is, as the name invokes, the endurance - the maximally long battery life, allowing the use for endurance sports like ultramarathons, expeditions, etc

I am currently using a $350 Suunto Race S. It can last 30 hours with multi-band GPS, 50 hours in GPS only mode. That is with AMOLED display. Suunto Vertical with MIP display has battery life that exceeds Enduro - up to 90 hours in multi-band GPS with solar charging. But even Race S battery life is more than enough for even the most difficult mountain 100 milers. By the way, Suunto has offline maps too, and dare I say, I much prefer Suunto's implementation of maps compared to Garmin's. 

trux said:

If you are an ultratrail runner, then the high accuracy is of no special interest, and you won't care about it, since it does not bring any advantage.

I am a trail ultrarunner, and I care very much about the GPS accuracy for a number of reasons:

1) GPS accuracy translates into distance and pace accuracy. Fenix 5, Fenix 6, and Enduro 1 were quite terrible in that regard, typically losing 5% of the distance on trail that I usually run on. That's quite a lot! 

2) GPS accuracy is also important for accurate matching of Strava segments. 

3) Poor GPS accuracy forces Garmin to buffer and smooth the current position on the map. The result of that is that the map lags behind by up to 5 seconds, which in some situations, when running fast, makes navigation difficult and forces me to stop This persists even in Fenix 7 and Enduro 3 as a legacy, I think. But if GPS was more accurate to start with, I don't think Garmin would have to buffer and smooth positions. In contrast, Suunto's map is precise to the second and rotates instantly and smoothly.

silentvoyager said:

GPS accuracy translates into distance and pace accuracy.

Not really. As I wrote, the watch does not rely only on the GPS position, and uses multiple data sources for the distance and pace estimation. In most cases wrong pace & distance estimates are unrelated to the quality of the GPS, and it can be easily verified by saving the activity as Course, or exporting it as GPX and loading to an external tool. I checked countless activities of other users, as well as my own ones, and if there were pace & distance problems, it practically always came because of bad accelerometer calibration, and not because of the accuracy of the GPS track.

silentvoyager said:

This persists even in Fenix 7 and Enduro 3

Yet people claim Enduro 3 is much worse than previous models. So if the lagging problem existed already at the previous models, with higher accuracy, increasing it at Enduro 3 would not necessarily help either.

Silentvoyager: with the proviso that I do not know exactly how far I ran, I have observed that the Enduro 3 typically measures slightly longer than the Epix 51mm but very close, and the same as the Coros Pace 3 from a mountain trail run on Sunday.

These are the run distances from the same run as my ‘stone circle’ offset example directly from the watches UI as recorded (miles, not km)

Regarding your Fenix 6x offset to the left question, while the Enduro 3 seems to show more offsets from actual vs. last gen. It is not as consistently offset as the Fenix 6 could be - on many occasions it can be almost impossible to separate the tracks. This is what makes the Enduro 3 offset errors stand out, when they happen. Because they do really stand out!

PS: I am making a bit of a point here in showing I do actually OWN the watches in question and have compared them and do have data behind this. This is from the real world, not the user manual.