How has the court interpreted the presumption that an official duty has been regularly performed?

"People v. Rath Packing Co., 44 Cal.App.3d 56, 65 [118 Cal.Rptr. 438] discussed the effect of the presumption that 'official duty has been regularly performed' (Evid.Code, 664), which is a presumption 'affecting the burden of proof' (Evid.Code, 660), and concluded that it did not relieve the moving party ... of the necessity to 'demonstrate that there is no possible way in which [the opposing party] can claim error in the weighing procedures used....' (People v. Rath Packing Company, supra, 44 Cal.App.3d at p. 65 [118 Cal.Rptr. 438].) Consequently, the court concluded that in the face of such a presumption, 'the resisting party need only demonstrate a "possibility" of being able to rebut the presumed ...' fact. (Ibid.)