eTrex SE has option to auto pause (to stop tracking activity log when device is not moving). Maybe your needs require this feature, but I suggest turning this feature off and always checking that pause is not enabled. Why? Because pause is a "great" way to miss your track log. There is enough internal memory to keep all points, even when there is no movement.
Several times pause seemed to be enabled from the turn-on for some reason and it didn't unpause even with movement, thus I lost some tracks. Notification about pause is very easy to miss (see screen shot). I still not sure why activity was paused, I did not pause it myself for sure. After turn-on always check for "pause" symbol presence.