s not sufficient); Regents of the University of California v. Kohne, 166 F.R.D. 463, 465 (S.D.Ca1.1996) (ten times in seven years did not suffice); Halliburton Energy Services, Inc. v. M-I, LLC, No. 06-53, 2006 WL 2663948, at *2 (S.D.Tex.2006) (business trips to Houston four times a year, staying approximately ten days each tri