Duolingo should convert checkpoints to "renew checkpoint" once a checkpoint is passed
It's disappointing to see all my skills lose their golden shine when I haven't logged onto Duo for a week (or more like a month). Also, the strengthening exercises become less useful because I end up going through basics again. It sort of slows down my progress.
If I could somehow renew my skills by taking a test or re-testing checkpoints, it would help a lot. I hope the Duo team would consider adding a practice test or renewal options to help renew skills more efficiently.
Duo really needs better features to collectively review older material. Something like a checkpoint revision option would be a very good addition.
When you have reached the end of the tree it's ridiculous to go again and again through Basics2 and "I am a boy".
The checkpoint test is only for those with more experience and once passed it cannot be taken again. I am afraid you just have to join the rest of us in following the timed repetition algorythm and refreshing weakened skills. Of course it is not mandatory if you feel confident that you know those skills, you can just ignore them and press on learning new ones.