How has section 654 of the Criminal Code been interpreted in the context of an attempted robbery and attempted murder case?

In Sandoval, the defendant demanded money at gunpoint from a convenience store clerk. The clerk began to comply but then stopped and tried to reason with the defendant. The defendant reacted by shooting the clerk and leaving the store without any further attempt to obtain the money. The trial court imposed consecutive terms for attempted robbery and attempted murder. (People v. Sandoval, supra, 30 Cal.App.4th at pp. 1295-1296, 1299.) On appeal, the defendant argued his sentence violated section 654 because both offenses arose from one indivisible course of conduct, and he had acted with the lone objective of obtaining money. The appellate court rejected this argument, viewing the attempted murder as a gratuitous act of violence and noting the crime of attempted robbery was complete when the clerk refused to hand over the money. (Id. at p. 1299.) "It was only after this that [the defendant], from point blank range, determined for his own purposes to punish [the clerk], or to assuage his own thwarted desires by seeking other and different gratification, by firing directly into [the clerk's] chest." (Id. at pp. 1299-1300.)