Many years ago when I was a teenager and learning to cook and bake, my timer and I were inseparable. If a recipe said to cook for 10 minutes, that's what I did. Not 9, not 11 minutes, 10 minutes exactly. My mother saw that I was a slave to the timer and said that she never timed cooking or baking. She used her nose. When she started to smell the food, she knew it was done. Her cakes always came out perfectly done.
I didn't pay too much attention to her and kept being a slave to the timer. Lately, I've noticed that I'm beginning to know when food is done by the aroma. A few weeks ago I got distracted while cooking and didn't pay any attention to the time. Suddenly I got a whiff of my meal. It was done and it was the best I had ever cooked that meal. I have no idea how long it was in the oven.
Today, I smelled the toast at the time it was perfectly done. Maybe my mother had something there.