Thanks, fair point. On the assumption that there are 'iPhone GPS' users here, I was trying to keep it crisp, but I guess a little more background would have been helpful!

I use the Memory Map app on the iPhone to record the GPS data. So far I've found no way of altering the rate of this data capture, unlike many dedicated GPS devices and perhaps smartphones. As you see from the more recent examples (
red in my table) every GPS change is recorded, with a typical interval as brief as 2-3 seconds. Leading to very close points and therefore a large total number of them.
An exactly flat walk of even as little as one minute could result in a good estimate of distance, say 250 ft. But, because altitude estimates by GPS are very inaccurate, even for dedicated devices, it would give a highly misleading estimate of gross ascent and descent, maybe over 100 ft a minute on my iPhone 6S+!
After transfer of the GPS file to my PC I open it in the desktop Memory Map application to display and work on it. From there I can save in the universal GPX format for work in other progtams, such as Google earth, GPS Utility, etc.
Naturally, I've emailed Memory Map too.
--
Terry, East Grinstead, UK