When will partial summary judgment be granted?

In his well-considered analysis of the issue of when partial summary judgment should be granted, Myers J. of this court stated in Mason v. Perras Mongenais, [2018] O.J. No. 1178 (S.C.J.) at para. 18: … where a trial is required involving the same parties, the same witnesses providing the same evidence about the same facts in issue as are relied upon for summary judgment, the risk of duplication and inconsistent outcomes is particularly acute. In such cases, the benefits of summary judgment as a cost saving or tool for efficiency are lost since a trial is required on all the same facts among all the same parties anyway.