Actually, for most autos, it's more like a "firm suggestion". The tranny will eventually shift anyway once rpms get high enough. On manual valve bodies, what you set is what you get every time. You want to shift to "1" doing 50 down the highway, well, ok, it's your neck, the tranny will do what you say. A stock tranny would just ignore you, though it might give you second as a happy compromise. Same for starting in second or whatever. Takes all the brains out of the tranny and puts it totally in your control, just like a stick with no clutch...