I found the cumulative elevation gain and loss statistics calculated by Trails are very inaccurate.
For example, in the following track, the elevation changes are about 130 -> 350 -> 170 -> 400 -> 290 -> 365 -> 130 (m).
If I calculated the elevation gain and loss manually, they are +220, -180, +230, -110, +75, -235, which sum up to 525 m of ascent and decent.
However, the number that the Trails app gives me are 1020 m ascent and 1036 m descent.
The numbers calculated by Trails almost double the amount of manual calculation.
I hiked the route personally so I know the ups and downs are quite simple like the numbers above. There was not much tiny ups and downs. I think the numbers calculated by Trails are too far-off from reality.
I recorded my hiking routes with the recommended Automatic mode and “Smart” accuracy setting. I also tried different settings but couldn’t see obvious positive improvement.
I know this calculation is a very hard. The phone might record lots of inaccurate points that are far from the actual location, especially when there are trees.
However, I really hope Trails can provide numbers that are more meaningful.