FYI, I have noticed in this course (JS Best Practices) that if I go to the challenges and then re-watch the video from there, when I return to the challenges, it has bypassed the challenge I was in and taken me to the next one. This has happened repeatedly in this course. I don't remember it happening in JSRT or the HTML/CSS courses I took.
I was in 3.25 and clicked "Rewatch video" to open the slides. I then clicked "Start Challenges", and was returned to the challenge....3.26! 3.25 was marked as completed.
So, I'm guessing this is a stack issue, if that is how it works online, but maybe it's an increment problem.
I went into the Unmasking HTML Emails course and was able to do the same thing.
Effectively, this allows students to do more than BYPASS an exercise (as can be done via the ToC); it allows them to FINISH it and have it marked as such EVEN IF THEY DO NOTHING. Someone can go through course after course doing this just to acquire unearned badges.