Suppose you have a Service Level Agreement to respond to customer inquiries within two business days. A customer inquiry is submitted late Friday afternoon or evening.
The customer's case should not be past deadline by Monday morning.
A datetime property should be computed using the Calendar library setting the value to Monday morning. That property would be used for Assignment Ready. The work should be completed by end-of-day Tuesday.
Suppose you were to take an App Build exam by logging into a Cloud Instance. The exam officially starts Monday morning (your local time) at 10:00am say. You have 3 days to complete the exam. The exam assignment is pushed to your worklist at 8:00am. You are allowed to open the exam case from your My Cases view in review mode, look at the requirements for each question, and sketch out designs. You are also free to open the assignment and begin building the exam whenever you want. if you do this however, your score will be lowered because you did not fully utilize your allowed design "think time". :- )
Goal or Deadline does not matter. You develop the solutions on a laptop, not on the cloud instance.
Optimistic locking would be used. The SLA would continue the flow after 3x24 = 72 hours have elapsed - nothing you can do to stop it.
Prior to the deadline would had to have attached everything you want to deliver such as solution zips, design documents, or test instructions. Videos tend to be overly large. A smaller, sped-up video perhaps.
This is all hypothetical of course, not how app builds are handled today.