On Desired Dough Temperature: Michael presents the water temperature calculation in a simplistic manner to introduce the concept. In reality, there is always additional heat exerted on the dough by the machine. This is called the "friction factor" and it varies according to weight of dough, size of mixer bowl, and speed of development.
In Michael's experience with stand mixers and small batches of dough, the final temperature will be about 2–3℉ higher than expected, which is relatively minor in terms of its effects on fermentation time. With experience, you will learn how much friction your mixer imparts on your doughs and can make adjustments for friction your mixer produces.