Clear before Cloudy

If you accidentally contaminate the "cloudy" vial with some of the "clear" insulin that is in your syringe and later another nurse drawing insulin from the "cloudy" vial gets some of that "clear" insulin into the dose she draws up

• the amount will be insignificantly small because it became diluted with a much larger amount of the "cloudy" insulin in the vial
  
• a scant amount of "clear" (short acting) insulin is going to exert its effects more rapidly than vice versa if the worse case scenario happens. With something like NPH you are going to be monitoring the patient's blood sugars for 12+ hours; with regular insulin 4+ hours only (has to do with the maximum length of the insulin's effect)