The following KB details how users/admins should be using the getDayOfWeekLocalTime() method in business logic. This method will return a numerical value between 1-7 as it corresponds to the number of days in a week. The breakdown is as follows:

1 - Monday

2 - Tuesday

3 - Wednesday

4 - Thursday

5 - Friday

6 - Saturday

7 - Sunday

This method should only used against date/time objects in business logic. Using the method for a date object will result in unexpected results as the method is specifically for date/time objects.

Ex:Improper use

var startDateTime = new GlideDateTime("2019-08-22 12:00:00");
var startDate = startDateTime.getDate();

gs.print("@@@ TEST DATE START " + startDate);
gs.print("@@@ TEST DAY OF WEEK IS " + startDate.getDayOfWeekLocalTime());

This will return a value of 3 instead of 4 when we pass in 2019-08-22 12:00:00 which is  Thursday

Proper Use:

var gdt = new GlideDateTime("2019-08-20 12:00:00");
gs.print(gdt.getDayOfWeekLocalTime());

This will return a value of 2 as the 20th corresponds to a Tuesday and we have passed the method in using a date/time object