I wish I had realized that the directions on websites can be completely contradictory. One school said on the online application: "Please do not send us copies of your official transcripts. Upload a scan of your unofficial transcript or grade report, and we will ask for official confirmation if you are accepted." In their Notes on Applying booklet, they said, "Every program requires two official copies of your transcripts before your application may be considered."
A different school had two different lists of required supporting materials at the departmental level, one on the department's subsection of the main school website, and one on the department's own separate website.
This made the post office very rich.