Here's a specific example and what triggered this topic.
Race was set to 50 minutes and 40 laps. I admittedly forgot it was 50 minutes and was thinking it was 40 instead, so I was checking the time shown on the ticker and thought there was 10 minutes left as it said, but halfway through the backstretch it set itself back to 10:59, which shows that it was actually on estimated time instead of actual server time. I believe there was actually about 20 minutes left in the session at this time.