Comparison to StS2 (8/11)
We also can look at this finding from a different angle - a chart showing how that percentage of "extra" or "anomaly" reviews changed over time, for the two games side by side. The big numbers on the left are mostly an artifact, since at a low number of reviews, they can all be treated as anomalies. Aside from that, look at the difference between absolute values. Even though StS2 has a somewhat similar shape, it peaks at 13% and rapidly drops below 1.5%, compared to FFW starting at an insane 40%+, dropping to ~15%. So just being "session-based" doesn't explain the tail, at least in this comparison.
0/0