So I'm just wrapping up learning the four basic groups and have a question on groups three and four. I know it doesn't matter which one you pick as long you stick to the rule(G3=Sufficient and G4=Necessary), but for speed purposes I created my own rule and wanted to know if there was ever a chance that rule could be wrong. So I always do the first idea and make it the sufficient indicator and the second the necessary. For the obvious reason that that would put them on the same side of the "arrow" consistently. But could I be setting myself up for a mistake? Does anyone else do this rule?