You spent three days shopping, thawing, and prepping. Now it's the day of, and the roast, the potatoes, the vegetables, and the dessert all need to finish within the same thirty-minute window. One oven. Four hours. A serve time that doesn't move. The day-of sequence is the part nobody plans.
You bought everything on the list. You thawed the roast on schedule. You even prepped the Brussels sprouts last night. But nobody planned the day-of sequence. When does the roast go in? When do you pull it so it rests while the Yorkshire puddings rise? When do the potatoes need to go in, and where, because the roast is still using the top rack? The shopping list was the easy part.
The roast needs to rest before carving. That window is when the oven is finally yours. Ready Time slots potatoes and Yorkshire puddings into that gap, with gravy and vegetables on the stovetop alongside. You're not doing oven Tetris in your head. The math already happened when you set your serve time.