It so often turns out badly for me. For example, I am making a pork loin roast with garlic and au gratin potatoes. I checked the website for Pork, and it said a loin roast the thickness I was preparing should be cooked 20 minutes per pound. That seemed a little low to me, so I upped it to 25 minutes per pound. The roast is only 1 and a quarter pounds, and it's been in the oven now for 45 minutes, and it's nowhere near done.
Also, the au gratin recipe I was using called for 2 lbs of potatoes. I used slightly more than that, about half of a 5 lb bag. The recipe also called for 1 cup of cream and 1.5 cups of milk. Now I've got potato and milk soup with cheese on top.
I really should just go with my gut. I almost used less milk and cream, but I didn't. I almost put the roast in even earlier, but I didn't. It's not a disaster, but it's not the beautiful dinner I had invisioned, either.