Although it’s very common, regardless of the tempo, for a drummer to play “1, 2&, 3 4&” (Spang, Spang-a, Lang, Spang-a, Lang, etc.), the most important thing is actually the quarter note pulse keeping time. Check out some Jimmy Cobb if you haven’t already. Even at medium and slow tempos sometimes all he’ll play is quarter notes, leaving out the “&s” all together (Freddie Freeloader is the classic example). At breakneck speeds such at “Jubilee”, this can be very helpful to remember, as playing quarter notes is an excellent way to survive that tempo for an entire tune. Also, Spang, Spang-a, Lang non-stop through an entire tune at this tempo might be a little bit too dense and get in the way of the blistering fast piano lines, though I have little doubt that Kenny could do it if he wanted to.
So, what I think it boils down to is that it’s likely Kenny is attempting to do two things here:
1. Conserve energy
2. Leave space for Bill (probably more so this one)
Two further things worthy of note, though:
1. Even when Kenny is only playing quarter notes, beats 2 and 4 have a little more “weight” to them. It’s almost not even an accent. Those notes just somehow feel a little bit “bigger” or “heavier”. So even when you’re not playing the “a-lang”, that emphasis on 2 and 4 is still present on the ride cymbal.
2. When Kenny does play three notes in a row on the ride cymbal it’s almost always on beats 2 and/or 4, where it would naturally be if he was playing spang, spang-a, lang.
Here is a sheet with various phrasings of Spang-a Lang in amongst a steady quarter note pulse. Push the tempo just a bit past your comfort zone and with your hi-hat on beats 2 and 4, play each example on the ride cymbal 4, 8, or 16 times.
As you get more comfortable try improvising. Play the quarter notes with the "weight" on 2 and 4, and then start peppering in the “&s” where you see fit.