'Complete By' field on an ILT assignment

Summary

Why is there a complete by field when assigning a specific ILT when the ILT carries it's own dates

Content

Hello,

Can someone please explain why, when assigning an ILT offering as a manager, there is a compete by field? I would expect the system to recognize the dates of the actual ILT and have that be the due date for the training. It doesn't make any sense to give a due date to an ILT offering that has it's own dates. Attachment with screenshots included.