I note at our HS, you only need to move a college to Applying in SCOIR at least 10 days in advance of actually applying (to trigger the counseling staff getting in all the documentation).
So presumably our kids sometimes move a lot of colleges over to Applying only after the mid-December early notifications come out. But that will presumably be a function of how many kids are doing ED I, or otherwise are done if accepted EA/REA, and then how many are not accepted to such a college. Which could well be a variable each year.