I'd say the accuracy of seasonal closures and roadworks is correct in 3 out of 4 cases. On a road I used to travel a lot and which will now be closed for several months due to a landslide, myrouteapp web won't let me pass through it. On another road that passes through a mountain pass, it lets me pass through if I disable the seasonal closure, but that road isn't closed seasonally.
I once happened to be driving a route I usually take and while navigating, myrouteapp next kept telling me to turn back. But since I'd driven that stretch of road a few days earlier and know it like the back of my hand, I thought myrouteapp next had crashed. Instead, I discovered that that day, and only that day, the road was closed.