The tricky thing about cooking more than one ingredient is that they often do not take the same time to finish cooking. For instance, in this dish I serve carrots, asparagus, and potatoes along with the steak and all three cook at different times. This makes timing difficult as the goal is to have everything finish around the same time. This way nothing becomes dry or gets cold.
Little things to note when calculating when to start what ingredient are things like the time it takes for meats to rest, the time it takes for potatoes to reach an edible temperature, etc. When everything finishes at the same time you get the maximum flavour out of every ingredient. Timing is often overlooked and underrated. Getting it right makes a massive difference.