Hi Arthur, welcome to these forums.
While there are theories on this, there are probably about as many theories as there are DJs. And, as you might guess, the DJs that grow popular are the ones that toss the theories overboard and just “do” their thing.
And really, if DJ-ing could be caught in fixed playlists/sets, mathematical rules and such, there would be succesful automated DJ solutions around.
It’s the premiere reason we always say the the absolute number 1 skill for succesful DJ-ing is Knowing What Must Come Next.
As much as you love harmonic mixing (and most of us have been to that place when we got seriously into MiK), if you were to only do harmonic mixing, your sets would become boring. Being able to make big BPM jumps or genre switches helps keeping the audience alert and on their toes, wondering what rabbit you will pull out of the hat next.
I played a private b’day party a while back. It was rather impromptu, I was supposed to bring a mixer, PA and some mics because some people wanted to play/sing live music. Last minute they asked me to bring my controller and DJ the second half of the evening.
With no time left to prepare for the gig, sort out any playlists or anything, I just went and winged it. Turned out to be a good night with everybody on the floor, dancing and sweating. Several compliments afterwards with two or three people commenting on how “they were often surprised and came to become curious about my next choice”.
To me it wasn’t a good night as far as mixing (technical and harmonic) went, but I had fun, the crowd loved my choices and it was just a fun night.
Point in case, preparation is good, but it should be done in addition to being able to do one “by heart”, by knowing your collection intimately, not having it bigger than you really need and frankly getting as much live experience as you can get.
Courses on here can help your efforts. Lke the Serato Ninja course (learn all the ins and outs of the software, from installing properly and setting the best settings to fine-tuning to your worklow) and How To Digital DJ Fast (none of the trial and error stuff, quickly learning what to do and how to properly practice it. Not only technical skills, but collection building and playlisting and such as well).
Hope that helps a bit.
Enjoy your time here!
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