Thanks for your request and the time you spent exposing it.
Generally, I would agree with you. We considered this option while organizing, but then discarded it.
When you receive a test after a job interview, you usually have a fixed deadline to respect. You will not be able to do updates or fixes.
This jam goal is to expose talent to the industry, so we want to weight what any of you can do in a week. We need to value the skills of every team, and that would become tricky if constant updates are made during the rating period.
As the judges are all professionals, be sure they have knowledge and experience to understand what a team suffered with. Furthermore, they are surely aware that the most of you are not aged developers, so their evaluation considers that as well.