For Workflow Automation Schedules, you can add custom schedules for your workflows. You can find them from your admin page by going to CRM > Workflow Automation Schedules

From there, you can see the default schedules in place.

In order to set a custom schedule, click on 'Add Schedule' on the top right to begin.
You can give a general start and end time for your schedule.

The section below shows the custom schedules that you can set. You can skip the day by selecting yes under the Skip column.