I would say for most events you dont have remod, you can generally get away with one set for everything. It's pretty easy to determine if a mod is good or not. If no speed at all - immediate delete. Depending on the color theres certain speed thresholds for keeping it (could depend on stage of the game too, early on you'd be desperate for anything with speed vs later game players that can be more particular). Never use the auto mod recommendations. Swgoh.gg has recommended sets for every character. It's probably one of the most important things about playing the game.