There are 2 primary ways people use my tool. One is to join activities end-to-end into one long activity. The other way people use the tool is to interlace the data from two overlapping files. A common use case is to combine the data from a trainer and a heart rate monitor.
If you are merging two overlapping files, you probably couldn't hit the start button in the exact same second for both devices, so one thing you had to do with my tool is to manually enter the start/stop time in order to trim off the non-overlapping "tails" before and after your workout. Here is an example of the "tails" I'm talking about:
So, to make it easier for users, I have added a "smart trim" button that appears when the tool detects TWO (and only two) activities with 70% or more overlap. Here is what it looks like after you click the "Smart Trim" button.
Hope that feature makes things easier for some of you!