Preoperative team briefings, or time outs, are now considered mandatory in operating rooms. These briefings, which may be structured around a formal checklist, are intended to create shared situational awareness and thereby avert serious errors such as wrong-site surgery. Resistance to implementing preoperative briefings has been encountered on the grounds that operating room efficiency may be harmed. However, this study conducted at two British hospitals found that operating room start times were not delayed after briefings were standardized, and operating room personnel strongly felt the briefings improved safety. A prior study also found that briefings actually improved operating room efficiency by preventing unexpected procedural delays.