Activity straight lines

First off, where are you VIEWING the activity? On the device itself? In the Explore mobile app? On MapShare or the Map tab at explore.garmin.com? Garmin Connect? Someplace else?

Also, just to be sure, are we talking about the "sent points track" (the data that is uploaded to the servers via Iridium satellites in more or less real time) OR the "activity" (fka "logged points") (the data that remains on the device until you sync)?

Since I don't know the answers, let's look at the fundamental data gathering.

For the "activity" (logged points), you need to look at Setup > Recording > Record Method. Chances are that you are set to "Auto". This means that the device decides when/if to record a point. This is supposed to record just enough points to capture significant inflection points in the path. Nobody knows exactly how this works. In my limited experience, it's not entirely reliable. YMMV. Personally, I prefer Time. This brings the Interval setting (same Recording Setup page) into play. These two settings together allow you specify EXACTLY how often you record a point. The value you need depends on how fast you are moving and the desired "resolution" of the track. Do be aware that very small time intervals (I think maybe 30 seconds or less) keep the GPS radio on at all times. This will affect battery life.

For the "track" (sent points), look at Setup > Tracking > Moving Interval. The smallest available interval depends on your plan. All but the most expensive plans start at 10 minutes. The very expensive plans start at 2 minutes. The device will send a point at the specified interval. The only exception is if the device cannot get a fix at the designated time. In that case, it skips a point. If you stop moving, the device automatically increases the send interval to 4 hours. When you begin moving again, the interval reverts to what you set. Even at a walking pace, the sent points are normally too far apart to provide an accurate track. The main purposes here are (a) safety and (b) sharing with the folks at home.

One aside about display on MapShare or the Map tab on your account at explore.garmin.com: UNTIL you sync, the only thing that shows up on those maps is the "sent:" points. Those points are connected by straight lines. AFTER you sync, the web site is supposed to combine the sent points with the logged points - resulting in a "smooth, accurate track" with visible "round icons" at the sent points. Most of the time, this works. But I have seen a few situations where the two are not correctly combined. (In my experience, when this happens, you see both the straight-line-connected sent points AND a separate, "smooth" track representing the logged points. Again, YMMV.)