What is the test for extending time for cross-examine?

In the course of argument I raised with counsel for the parties what the appropriate test may be for an extension of time, where that is sought in regard to an opportunity to cross-examine. I invited counsel to address the possibility that the well established test in Grewal v. Minister of Employment and Immigration, [1985] 2 F.C. 263 (F.C.A.) might be appropriately applied. I am grateful to counsel for their helpful comments.