eriod 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) (finding seventeen month period insufficient to show continuity); Religious Tech. Ctr. v. Wollersheim,