Even a slick shifted trans, [every other tooth ground off gear ring and syncronizer ring], has to be clutched to shift at WOT. A planetary trans, [Like Lenco], can be shifted without the clutch.

Speed shifting is when you shift without the clutch, you pull out of gear as you let off the gas and when the engine RPM drops to the right speed it will pop into next gear. That was called speed shifting and was common before the invention of syncronizers. It is very slow but must of been faster to do that way before syncronizers.

Herb Mclandless needs to chime in on this one as I am sure he ran stick S/S cars.

I have seen several old in car drag strip films from the sixtys and you could see the driver bounce the clutch as he was rowing through the gears.