I am an avid user of my Garmin watch. Sadly I fear that I am about to become less avid. I will soon reach level 6 only by virtue of gathering all of the low hanging badges. However level 7 appears to be out of my reach forever. I am probably an average Garmin user. I won't run a marathon or ride a century, but I exercise every day and I enjoy earning points and leveling up.
I believe that under the current system, the average user will never reach level 7 and will therefore lose interest and motivation. I think it would be good for the users and Garmin, if they would make it easier to advance. There would be no harm to anyone if earning 200 points would advance one's level. There's really no need to require 640 points or 1280 points to advance.
Regarding the challenges and badges, I think there's no reason to stop awarding points for yoga or walking after 200 activities. Why not award 4 points for every 50 activities of yoga, walking, running, hiit, swimming, weight training.
I think the badges for activities on special days, such as Global Cycling Day, add a nice feeling.
The monthly badges are great, but I'd like to see a little more variety.