Working hours (d) is defined in line 116 as end_hour - Start_hour minus 1. This appears to exclude the fact that the end_hour is different than the end time.

Example:
If end_hour = 1700
End time = 1800

Comment also seems to indicate that this line is calculating the total workday span when it may be actually intended to calculate the official workday span with at least 1 one hour break.

I believe the intention might be d <- (end_hour - start_hour)