ir.1999) (stating that the Second Circuit "has never held a period of less than two years to constitute a `substantial period of time' "); Hughes v. Consol-Pennsylvania Coal Co. 945 F.2d 594, 611 (3d Cir.1991) ("[T]welve months is not a substantial period of time."); Vemco. Inc. v. Camardella 23 F.3d 129, 134 (6th Cir.1994)