You don’t miss out on any of the items he gives you after completing the photo shoot because you only progress through when you come so if you miss a few days you’ll be in the same place where you left off. If that makes any sense? The only reason I know this is because someone else on my Island skipped a day and is now essentially a day behind me so when she goes she gets the item I got yesterday. I guess the only downside is less heart Chrystals when the event ends. But maybe someone else knows something I don’t.