My technique for this kind of thing is like this: All decks are set to auto. Before doing anything, I'll sync all playing decks to the master deck, and turn on key lock for all playing decks (I like to speed up/slow down without changing pitch). Then my shift button turns my pitch faders into 50% range faders, which generally is enough for me. Then I use the pitch fader of whatever is the master deck to speed everything up/down.
Because for some reason in Auto mode Traktor sometimes reinterprets which deck is master while doing this move, I have set the shift button to momentarily switch to Internal Master Clock mode while held down. This way, when I move the pitch faders, Traktor doesn't get confused and send things out of sync when it thinks the fader I'm moving is no longer the master deck.
Seems people are conflicted about this technique. While I'm not a fan of using it for dense parts of tracks you've already been playing, I think for spacy pads and sparse breaks, you can drop a couple loops and use it to really good effect. Bassnectar uses it a lot, drives the crowd frickken nuts.
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