This method is the counterpart of the two-stage cake mixing method. There is more liquid in cake batters, so it must be added in two or more stages in order to blend uniformly. Low-moisture cookies, on the other hand, can be mixed all in one stage.
Because all the ingredients are mixed at once, the baker has less control over mixing with this method than with other methods. Therefore, the one-stage method is not frequently used. When overmixing is not a great problem, as with some chewy cookies, it can be used.