@MickJay
I looked at this yesterday, and didn't respond as I just couldn't understand the issues.
Can you clarify exactly what you are trying to do?
Are the workdays always in sequence, or can they have gaps. If in sequence, then you should only need the first day and the last. eg, Tuesday, Friday - If they have gaps, then how do you deal with the gaps - Monday, Tuesday, Thursday, Friday, Can the days straddle a weekend. Can your sequence be more than 6 days. ie Monday...Monday?