Is discoverability a valid cause of action for purposes of a limitation period?

The only issue is whether discoverability applies: I am thus of the view that the judgment of the majority in Kamloops laid down a general rule that a cause of action arises for purposes of a limitation period when the material facts on which it is based have been discovered or ought to have been discovered by the plaintiff by the exercise of reasonable diligence... Central Trust Company v. Rafuse, 1986 CanLII 29 (SCC), [1986] S.C.J. 52 at para. 77.