Fort Brown Villas III Condominium Association, Inc. v. Gillenwater, No. 07-1028, 52 Tex.S.Ct.J. 632 (Tex. 2009) holds Rule 193.6 applies to a summary judgment hearing to exclude evidence due to untimely discovery response.  In Gillenwater the expert needed to defeat summary judgment was not timely disclosed.  However, Rule 193.6 applies to all discovery requests.  If the movant gets a quick setting, over 21 but less than 30 days out, Rule 193.6 will be in play (the expert deadline may already have run).  Tactical suggestion:  file MSJ response, supplement discovery answers, coupled with motion to allow late supplemention, along verified motion to continue hearing date, supported by affidavit of attorney showing necessity of evidence and to make supplementation timely.  See Rules 251, 252, 166a(g).  A further motion to allow late designation of expert will also be required in some cases, as in Gillenwater.