By default, the time division in the WinForms ScheduleControl is 30 minutes per hour. However, this can be customized using the DivisionsPerHour property. The allowed values for this property are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, or 30.
For instance, setting the DivisionsPerHour property to 4 creates 15-minute time slots by dividing each hour into four equal parts.
this.scheduleControl1.Appearance.DivisionsPerHour = 4;
Take a moment to peruse the WinForms ScheduleControl - Customizing Appearance documentation, where you can find about customizing appearance properties.