You are right that there is no concensus on how the darn thing works.
However, there is concensus that yours behaves just like all the rest out there.
It holds more than 15 minutes of data, and no more than 2000 minutes.
That's all we know for sure.
It may be something in between.
There are some hints it may be 1000 minutes of driving, or collects 2000, then dumps the oldest 1000 to make room for a new 1000 minutes.
All possibilities.
In the long run ( over the whole tank ) the computer is pretty close.
-John