Louise,
The sales forecast due date falls on a Monday,
This is common. Assuming that you build to forecast, and assuming that the actual demand date of the forecast falls on 'Monday', this would mean that the business model is that you build your product during the previous week according to the forecast, and then you sell it via sales orders on Monday/Tuesday/Wednesday/Thursday/Friday of the current week. On Monday, you have a substantial amount of stock, and by Friday, all of that stock that you built (during the previous week) for the forecast should ideally have been sold via sales orders.
On Tuesday, you no longer care about this week. It is now time to begin building toward NEXT week's forecast.
which means after the Monday the sales forecast cancels itself.
Well, that's an odd way of putting it. Sales Forecasts don't generally 'cancel' themselves. You may, however, have configured your system such that you ignore forecasts before 'today', since it typically makes no sense to build toward a forecast that lies in the past. When you build to a forecast, you typically build toward future planned requirements. The past is past.
which leads to the problem of only being able to plan on a Monday.
I don't understand this statement. Unless there is infinite capacity, on Tuesday, most companies would begin building toward NEXT week's forecast. This would happen throughout the week.
is there a way we can change the due date to being the full week?
anything is possible. As alluded by expert Caetano, some companies spread the weekly forecast requirement such that it is equally distributed during each workday of the week, instead of just creating a single demand on Monday. MD67.
Best Regards,
DB49