There are several areas in AltaMail that allow you to set schedules such as notification quiet times or account productivity settings.

When you open the schedule screen, you can enable days using the switch button on the right. By default days will be grouped into weekdays and weekend days. Tap on the "..." button beside the day names to split display all of the individual day names. Tapping on the "..." button again will close the day group and set all of the day schedules to match the top day in the group.

Tap on the start or end time to edit the times. When editing the time, tap outside of the time selector to select and close the selector.

In most schedules, you can add multiple times per day. Tap on the "+" button to the left of the Start time for the day you are editing. This will add a new time range for you to edit.

To disable the schedule completely, turn off the switches to the right of each day.