what you said is true for for the old non-syncronous transmissions. The meaning has shifted (no pun intended) to mean using the clutch when entering the next gear to allow it to go in smoother/faster. This can best be seen when downshifting into first while moving at a decent speed. The tranny won't let you shift into first unless you let out on the clutch a little then it goes right in. This can also be seen when the car is really, really cold in both up and down shifts. The same applies for upshifting. It is especially useful to quickly shift a transmission whos syncros don't allow for a quick shift with the clutch still to the floor. try it in a truck for a good point of reference.
