Hello,
I agree that maxspeed:practical above maxspeed is debatable, but hear me out, and let me know what you think:

On the Polish OSM Wiki (actually not anymore, up until yesterday, someone just pasted the EN version into PL), the maxspeed:practical tag was described as "reasonably achieavable speed putting aside the speed limit". And while that is different from the EN description, I think some differences between countries and their interpretations are ok.

I queried the API for the uses of maxspeed:practical, and both in PL and outside there are many uses where maxspeed:practical is > than maxspeed. My intepretation (and use) of this tag is, "what speed does an average user drive here" - which is what the practical speed kind of is. Not the fastest, not the slowest, but what most people do here. And that in some cases means a bit above the speed limit.

I'm using these values for tuning a self-driving agent for cars, not to tell it how to drive, but to be able to compare its actions to the average speed of a human driver - hence the "real" values, even if they go a bit above the limit are better, because they reflect human driver. The self-driving hardware provides logs with telemetrics of the rides, I'm trying to use a rounded average in good conditions without traffic of how people drive. Capping maxspeed:practical at maxspeed is not the end of the world for me, but I'm not sure of the benefits. The consumer of the data can always discard the values higher than the speed limit, so we would only be removing information making it reflect real-life less - that's my opinion on this.