Inaccurate timing of the RTI

Hello municipality, I’ve been reading here for a while, but I don’t know that the following has already been the subject of discussion. Who cares about the utopian indication of the driving time of the RTI, which is especially noticeable with longer distances. Am I constantly travelling too fast, or can RTI not count on it. How can it be that with a distance of 680km the thing shows 3 hours too much? Had only a 1r with Navi last week and the correction of the ANKUNFTSZEIT played on a distance of 120km with 20% land road share in the minute area. Does the other thing go that way, or is it just annoying me so much? Greetings Michael