When a Stage has closed and the Draft Schedule(s) button (labelled Redraft Schedule(s) in the case of Stages that have been drafted previously) is clicked, a background job will be scheduled for the very near future, to generate the variations using the Lottery module's processing algorithm.
Once that job and the algorithm has completed its processing, you will have one or more Schedule Variations, each of which represents the outcome of one attempt or iteration of the algorithm. Each Schedule Variation may be slightly different, and this is because the algorithm uses randomization to shuffle the list of Learners, ensuring impartiality.
After the variations are generated, they can be reviewed in the Variations Overview one at a time. If an optimal variation is found, it can be merged into the Lottery's working schedule, which can be published at a later date when ready. If for any reason there are no viable schedule variations created from the algorithm's processing, you may select the Redraft Schedule(s) button on the Stage Card in the Stages Overview.