One of the most common questions that I get is why the second hand disappears after 5-10 seconds on my watchfaces.

Garmin watchfaces have 2 modes:
  High power mode where the screen updates once per second
  Low power mode where the screen updates once per minute. 

When in low power mode the seconds are not displayed.  The watch switches from high power back to low power after about 10 seconds, and this is controlled by Garmin.  Generally we can’t control that except possibly by changing the backlight timeout setting in your watch settings (not the watchface setting).

On some watch models you can keep it in high power mode longer by pushing a button or tapping the screen. Repeating this you can keep it in high power mode much longer.

Many people ask if I can support "Always on seconds" to keep the second hand on constantly. I did this on the GlobalSync, Musee Reborn, and Aerospace+H2 watchfaces. On other watchfaces there is not enough memory to support this. More than half of Garmin's watch models have very limited memory available for watchfaces. If I supported it, there would be less than half the features. Also, always on seconds drains your battery much faster.