"Strengthen Skills" is no longer effective.
Hi, I have noticed that ever since the new design was implemented, the "Strengthen skills" feature is not as effective as it used to be. I often find myself having a great timed session of maybe 17-18 correct answers, without any (or only one) skill turning "golden". When I specifically practice those skills, it becomes golden even after just 1 correct answer (and 19 more "skips").
It just doesn't make any sense. Is it a bug?
EDIT: Thought I'd add a screenshot just to be clearer: