500 track points is the limit for older GPS units.
10,000 track points is the limit for for GPS units of the generation that saw the Edge 205, Edge 305, Edge 500, Edge 605, Edge 705, Etrex 20, 30 come out etc. Not sure of the track point limit of Edge 810 but anecdotally I believe it has the same limits.
A 200km track generated online is unlikely to exceed 10,000 points but it has certainly been seen on a 300km track. I have seen some RWGPS tracks with a trackpoint every 7m even on straight roads. This is about 28,000 track points for a 200km ride. An unnecessary number. By default I run all the tracks I intend to navigate through my own tool, this includes tracks I have generated myself for DIYs etc.
But it is not just about these upper limits for tracks. A clean track with fewer trackpoints is also less likely to glitch the unit. An example is tracks with timestamp data in them. If some Edge units encounter timestamps in a track they are trying to navigate then they will glitch / fail. Etrex are more tolerant than Edge units and less likely to glitch but they will encounter problems if you try and navigate a track above its track point limits.
Certainly since I started only using cleaned / filtered tracks I have not had a problem with glitches / failed navigation.