As you work up the roof, enter the measurement from top edge of the last full sheet to the hip center line, and hit Calculate to display diagram with the correct bottom length measurement to form the cut angle.

Hit 'Save Off-Cut #1' to save (and draw) each entered sheet's off-cut to the list at bottom of page. When you cut each sheet, mark it's off-cut with the number from the off-cut diagram.

As you enter new 'Short Measures', if any existing off-cuts match this new size, the off-cut match number will be listed above the off-cut diagrams.

If an off-cut matches, use it instead of cutting a new sheet, and click it's diagram to remove it from the list of available off-cuts. After entering a few off-cuts, drag the 'Short Measure' slider to see matches. Off-Cuts that are too short for currently entered sheet cut are marked in red. Off-cuts that are longer are marked white with the extra length displayed. If there's no exact match, cut from the off-cut that's closest to (over) the size required.
with Off-Cuts.
After you have some off-cuts saved, hit 'Save All Off-Cuts' to save all currently visible off-cuts. When you return to this page, or hit 'Load Saved Off-Cuts', the off-cuts will be restored.