Take https://flightaware.com/live/flight/UAL328/history/20210220/1925Z/KDEN/PHNL as an example.
The default replay speed is 10x.
The flight has the duration of roughly 25 min according to the timeline below, from 01:04pm to 01:29pm.
10x would be 2.5min, or 150s.
Now, click “replay” button, and use a stopwatch to time it.
It only takes 15s, or 100x speed, to finish the animation.