I’m not sure whether there are third-party apps that collect statistics… I was bored while waiting for new reviews and lessons, so I PHP’ed myself a stat-page. I’m posting a screenshot here as an exemplar of what would be really informative to have, in case the WK developers are looking for hints of how to improve the experience. Wonder what the other users would say.
The first graph shows the hourly stats for each section; the bottom left shows the cards movement between sections (the trend goes negative when more cards move, for instance, from guru to apprentice than to the opposite direction); the bottom right is for shiwing the percentage of critical words.

