About Traitors, should I (or do I need to) start with season 1? Or can I jump right into season 3?
Each Season is independent of another. Same general format across all the nations with some small differences.
Traitors UK did make a major-ish change (The Seer) in season 3 that you would notice being absent going backwards.
Another subtle change you may see are the 'reveal or don't reveal' at the end of the game.
Or the editing tends to get better over time on all reality shows - # of times you see a non-Traitor participant may mean something (or not).