727 shifting in drag race??

May sound ultra old school, but I don’t use a tach for anything other than staging my footbrake car. Same goes with the shift light.
I have found I can be more consistent/ repeatable by shifting the car by feel/ ear, than any other way.
The car tells me exactly where to shift it at. Last outing I ran the exact same number 4 times. The other times the car ran a couple of numbers slower or faster was condition related( cooler early morning or late afternoon) with better or worse DA.
My driving lately has sucked, but I don’t feel at any disadvantage to guys shifting with air or electric or staring at shift lights.