As there's three different Horizon Arcade challenges which you can complete at once this week, I thought I would save them until they were all available and knock them all off.
They are, for reference:
Season Events - Horizon Arcade: Mini Games - Complete any Horizon Arcade theme
Daily Challenge (January 13) - Horizon Mascot - Smash 5 Pinatas in Horizon Arcade Wreckage
Daily Challenge (January 16) - There Ford You - Complete round 3 of Horizon Arcade in any Ford
To do that in one you'd need to do Horizon Arcade Wreckage, smash five Pinatas, and at least finish the event while in a Ford. With Air/Chaos/Speed/Wreckage being on some kind of rotation (no idea what the pattern even is) - while Drift is inexplicably there permanently - that means waiting for a Wreckage event to come up.
Lots of people are complaining about it because... well, there isn't a pattern. And there might not even be a pinata round - I had two skills rounds and a pinata, but it's not guaranteed.
Having logged in an hour ago, I've so far had:
Good job it wasn't a Speed event, I guess.