I am following the 80/20 for years and there is no way back, even if I would try hard to break it. It feels so natural, if you internalized the principles, every training week end up more or less 80/20. :D I keep track of my training intensities with Tredict which is made for 80/20 running and training. You'll see your intensities of every run concisely besides every activity and also aggregated for the week, month, year in the calendar. If you begin with 80/20 this helps a lot!
Doing Elevation is hard, because there is no real source of truth.
It all depends on the measurement itself (barometric, GPS-based, none) and the smoothing and other algorithms the platforms applying in post processing. So, if you compare all the platform, you won't find exactly the same results for one activity. Especially the FR245 has no barometer, so it must be corrected by map data in the post processing.
You can find more information on the accuracy of altitude measurement in the Tredict glossary. My preferred training analytics software. :)
I can recommend Tredict for things like this. It has an freely configurable and decent evaluation section with aggregation and relations charts over self definable time ranges.
Also it can show records from two types if distance sources. First, records calculate by distance, this is what you are used to from all other platforms or, distance calculated from the speed, which often results in different record results. With Tredict you are able to switch between those. This enables you to compare the accuracy of your devices, GPS, footpod and so on. There is also a metric called "speed distance deviation¨", showing exactly this. Really interesting stuff.
You could an endurance analytics software like Tredict. It is displaying a clearly arranged form and fitness chart besides your training calendar., which helps you to balance your training. There is also a value called "Rest day" which I find very helpful for myself. Here is some description about it in the Tredict glossary: Training balance and determining training effort correctly.
Indeed, I checked again and you're right. Anyway I have another more complicated option for you :) https://www.tredict.com you can select there a part and will get average for that part, I just went there and checked to see if it re-calculate the data. I believe you can get there a few free trial months or even more if register via someone's affiliate link. So you can give it a try. There is also free Runalyze.com but either I did something wrongly or it behaves the same way as Garmin Connect
>Training load: You won't get any of that with Vivo/Venu watches, only with Forerunner/Fenix. However you can sync your Garmin Connect data to Runalyze for free (donation option available) to get athlete focused training advice that's even outperforming Garmin's offers in some aspects.
In fact both Runalyze and Tredict would not only provide you with the access to own analysis but they would give you the access to Garmin's data fields for Recovery time, Training Effect and Anaerobic Training effect which are hidden from the watch and Garmin Connect but still written to .fit files.