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