Well, using another program, I see that you did the following:
1) 15:49 minutes x 60 seconds = 949 possible tracks, and you had 951 tracks recorded.
2) 3:17 x 60 = 11820 possible tracks, and you had 11815 tracks recorded.
So, it is tracking every second as you have it set for.
Garmin Connect does seem to do some "smoothing" (I think that is what it is called). Here is your
shorter session opened in Gartrip. Not necessarily a recommendation on the software at this time, just a different view for now...
I could be a smart ass and say that all those forays into the trees wasn't good for tracking, but with the leaves being down and all...and the fact that I have used a FR many times under in the deep, dark forest would make for a weak argument. ;)
I do think that, besides the smoothing that certain programs do to the tracks, there is also the position of the antenna to be aware of when wearing the unit. Your unit being in up (running position) is going to track more accurately then having it pressed against your side.