If you create a One-Time Job as a Multi-Day Job, the Job will automatically be scheduled on the Dispatch Board based on the Start Date, number of days, and Multi-Day Include Days:
In this example, the first day of the Job would be 10/1 and the second day would be 10/2. Both of those dates are weekdays that would typically be worked. If, for example, you do not schedule work on weekends but a three-day job starts on a Friday, the next two days would be scheduled on Monday and Tuesday.
If you create a Waiting List Job as a Multi-Day Job, it will remain on the Waiting List until you move the job to the Dispatch Board. Once you schedule the job, it will follow the same rules as a One-Time job.
Team Size does not update when you assign the job from the Dispatch Board or Waiting List. If you want the number of days for the job to update based on the Team Size, you will need to update the assignment from the Master Job level.