Like others have said, mostly based off of experience and reference. For example, I've baked a pizza enough times _with_ a timer and specific, but different te

Like others have said, mostly based off of experience and reference. For example, I've baked a pizza enough times _with_ a timer and specific, but different temperatures set that now I need neither and can just adjust the temperature to what I'm used to and know that the pizza only needs a certain amount of time. The end result should be a certain way. As long as it gets there correctly then whether there's a timer/no timer it should be fine.