Just a some thoughts on a few lines from the introduction to Ari Hoenig's book Systems:
“In jazz or other triplet-based music, melodies which are written as eighth notes are often swung (played with triplet subdivisions). In this interpretation, the melody can fall only on the first or third triplet, but never on the second. After a while, this approach can create a limitation in your idea of swing. There was a time when the second note of the triplet was rarely played in jazz. Recently, however, it has become a more common part of the language and can be effectively used to build tension in the music. A large part of this book concentrates on hearing the second note of the triplet and understanding its correct placement.”
I would dispute the idea that jazz is triplet-based music, and that swing interpretation = playing a triplet subdivision. I would say it's triplet-compatible in a certain range of tempos, and interpretations, but that the triplets are incidental to the swing 8th notes. You can read more on that here.
As a practical matter, tempos are often too fast to be thinking about the whole triplet, and conceiving swing that way tends to bog down the time. Oh, hell, Bob Moses can say it better than I can— from his book Drum Wisdom:
“Perhaps some people have heard that jazz is based on triple meter or triplets, while rock and Latin music are based on duple meter or 8th notes. I think this distinction is a mistake and actually misleads people. The music I call “American groove music” is, for the most part, based on [8th notes]. There is a place for triplets, but [...]they're generally used on slower tempos.
[...] Thinking of it as triplets clutters the bar; the more subdivide the beat, the more tendency there is to make the music slower.
[...] The tempo tends to come down a little when people play a lot of triplets, and the same thing can happen if you try to keep triplets going in your mind. [...] Even if you are not playing triplets, if you are thinking triplets, you are filling each beat with too many notes. By thinking 8th notes, be they [swing] or straight, you are leaving the music more open. You can still play some triplets if you want to; however, I advise you not to think triplets.”
The large part of what I've been about with triplets is to be able to play them without stating them, if you can dig that. If you look at the common Syncopation methods, the goal is not to make perfectly-articulated triplets, it is to fill out the texture while playing a swing melody line consisting of quarter notes, 8th notes, and dotted and tied notes.
The middle of the triplet, in jazz, is a filler note, or part of a quarter note triplet. It also has some special functions: at certain tempos you could base a modulation to a Mingus double-time waltz on it. Or it can also act like a deliberately late-sounding hard shot in the ribs— a pretty harsh tension-builder. I once played with a Dutch Dixieland saxophonist who used that one a lot, and it was an effective device, but you don't want to hear it all night. And it can be used to take the groove into an African-sounding direction— the middle of the triplet is more of a felt thing in that music. But in general it's subordinate to the 8th notes, and I would be wary about making it a permanent feature of your swing conception. To me that creates a very artificial swing feel.
And finally, for all the time we spend working on triplets— and I do work on them a lot— I can't help but notice how much of what I (and the players around me) play is not triplets, and does not sit on a triplet grid. Listen for it.
[h/t to AA for inspiring the conversation, and post title.]