A method and system for automatic in-vitro diagnostic analysis are described. The method comprises adding a first reagent type and a second reagent type to a first test liquid during a first and second cycle times respectively, the addition of the first reagent type to the first test liquid comprising parallel addition of a second reagent type to a second test liquid during the first cycle time, and the addition of the second reagent type to the first test liquid comprising parallel addition of a first reagent type to a third test liquid during the second cycle time, respectively.