Live recordings like disco or rock can be a challenge, but like most parts of DJing, it comes down to knowing your music and using your ears. Knowing where the beat wobbles off a little and keeping your other hand on the jog to adjust on the fly. Being able to hear those beats drifting around and knowing how to layer the other track on top. The good thing is that detailed waveforms in most software help with this – you can see the beat that is off and nudge your other track along accordingly before hearing that off beat. Before the waveforms we had to just remember those variations were coming.
Now for a real hoot, try doing all this with a live band! You’ll be grey by the end of the night. haha