A review session ends with its own summary: the 
Session Statistics button, shown alongside Return Home on the session-end screen described in The review session. It appears whether the session ended outright or is paused on the near-due leeway countdown; either way, it opens the same screen with the same data.
Session Statistics is separate from the persistent tiers covered elsewhere in this section. See How statistics work for how the two relate.
Performance
The Performance card is a donut chart of this session's ratings: Again, Hard, Good, and Easy. Only ratings you actually used appear, both in the chart and in the legend beneath it.
By default, the center of the donut shows the total number of cards studied. Tap a segment, or its matching legend entry, to see that rating's own count and its share of the session as a percentage. Tap it again, or use the Back to total button that appears, to return to the overall count.
Review Timing
The Review Timing card breaks down the time you spent reviewing:
- Total Session Time: the combined time across every card you reviewed this session.
- Average review: total time divided by cards reviewed.
- Shortest review and Longest review: your fastest and slowest single card.
Each of these times how long the back of a card was visible, from the moment you revealed it to the moment you rated it. Time spent looking at the front, before flipping the card, isn't counted.
Durations under a minute are shown in seconds, like 12.34s. From a minute up to an hour, they switch to minutes and seconds, like 05:30. An hour or longer switches again, to hours and minutes, like 01:15.
A snapshot, not a running total
Session Statistics only describes the session you just finished. Close it, and that breakdown is gone: it isn't saved anywhere, and reopening the app won't bring it back.
This is different from Global, Deck, and Card statistics, which accumulate across every review you've ever done. If you want to see how a rating you just gave fits into your longer-term history, that's what those persistent tiers are for, not this screen.