I've been using a variety day to experiment with the cluster sets a little more. What I like the most is the extremely structured progression it allows and promotes. It is very easy to alter the rest periods, the reps, the duration, the load, power output, etc. I started looking at the intensity number of lifts (INOL) for a few different variations and think I have a good enough starting place to begin replacing the individual training sessions for my annual cycle with these clusters.
I've also been experimenting with some alternatives to the tempo runs I had been doing with shorter faster intervals and the LED with the swing fartleks. Here are some of the polar readouts.
Swing Fartlek:
I have become a huge fan of these. These have become my favorite for aerobic day. Each of the rounds is 25min and the longer session is 3 rounds.
Split Intervals (600m at date pace, [1' rest], 300m at goal pace, [5' rest])
The second part of the split is almost difficult to go slow after the short rest. I like these a lot for pace training. It's quarter and eighth of the target race distance in my case.
Split Intervals (300m at >goal pace, [1'], 200m @ >GP, [1'], 100m @ >GP [3'])
These faster intervals are for peaking and attempting to target buffering hydrogen, or whatever else causes fatigue a few weeks out from a race.