I use a 3 week progression, as at the end of 3 weeks is where I see the biggest gains from these intervals, and after I plateau.
typically I start with 3x8 (total 24' work)at the lower end of the intensity (like 110% ftp), progress to following week, 5x5 (total 25' work)a little more intensity, and finish with 3 sets 3x3 at 120% (total 27' work). = recovery for all. all feel the same, very heavy breathing, legs full of lactic acid for the last minute of each rep.
I respond big at the end of the 3 weeks, then very diminishing returns so I move on to more awc stuff in the next block of the peaking process.