You can do either!
WorkReels is designed to be an experience that is customizable. You should do whatever feels right for you and your organization.
That being said, we'd recommend at least reviewing the first few videos as they come in. This will help you to make sure that your talent has a good understanding of WorkReels and are filming videos that you'll be able to use.
You wouldn't want to get everything filmed and then realize that they misunderstood something and it all has to be filmed again.
Try checking the storyline every few days to see what new videos have been recorded. And remember you can always provide guidance by commenting on a video.