When a shift worker works his first scheduled day off, it shall be considered as a Saturday and shall be compensated at the time and one-half (1-1/2) rate. When a shift employee works his second scheduled day off, it shall be considered as a Sunday and shall be compensated at the double (2) time rate. When a shift worker works on his scheduled day off for a holiday, he shall be compensated for the holiday plus double (2) time for all hours worked on such day.