I think you all are talking about a DSG-type "Direct-Shift-Gearbox" transmission. Think of it as two gearsets and clutches, 1-3-5 and 2-4-6. As the trans pre-selects the next gear, one clutch releases and immediately the other engages far quicker than any human ever could.
Earlier types used wet clutches not unlike a motorcycle clutch. Later dual clutch transmissions went to dry clutches probably to keep friction material out of the fluid as the clutches wear and to increase service intervals which many motorists failed to follow leading to prematurely ruined trannies at $5000+ a pop.

I think the fluid changes were supposed to happen every 45,000mi. The moral to this story is Don't Blow Your Tranny!
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