Seems in Canada that it depends on one's position in the company.

http://www.canadianlawyermag.com/4132/notice-is-a-two-way-st... points out that

> In Aquafor v. Whyte, Dainty, and Calder, the court held the four and five weeks’ notice provided by two departing fiduciary employees was sufficient

But that wasn't a blanket decision. Had Aquafor been able to show the judge that that they needed "12-18 months" (!) notice, then it probably would have had a different result.