In what circumstances have courts upheld a finding of aiding and abetting in a robbery case?

In People v. Campbell (1994) 25 Cal.App.4th 402, a case involving an attempted robbery with a firearm, the court upheld a verdict over a sufficiency of the evidence challenge on an aiding and abetting theory, noting that because the principal and accomplice jointly approached the victims and engaged in separate criminal conduct, the accomplice "did not independently happen by the scene of the crime." (Id. at p. 409.) It held such conduct was a "textbook example of aiding and abetting" in that the accomplice "played an affirmative supportive role in the [principal's crime] and was not simply an innocent, passive, and unwitting bystander." (Id. at p. 410.)