I says most schools and noted when people talk about rolling that they talk about Pitt but far more schools are rolling.
Pitt is pushing demand - to imply you need to be early. They are using FUUD tactics to get early apps. I know plenty who applied later - on recommendation from others and got in - the next calendar year.
They publicly state Dec 1 for merit consideration.
Incoming first-year students who have a completed application for admission with all required materials by December 1 are automatically considered for University of Pittsburgh academic scholarships.
But you are talking about Pitt. As noted in my comments, I was talking about most schools, not one specifically.