It is rather a conceptual line to differentiate between accumulation period (where training stress - load progressively increase) and SPP (MxS and EXP) where the athlete need to maintain a given workload. This concept actually came from Elite Concepts e-book. And yes, there are oscillations in the curve (emphasis/quality switch, opponent, reaction of the athletes, travel, opponent, etc, etc) and can also be seen from load-level of the microcycles within each block (A, L, I, R).
Basically, it is not something you can ‘measure’ numerically (maybe total trainign time, or session RPE * training time, etc), but the basic concept behind it is that once the athletes develop work capacity (in accumulation period), the training stress should be more or less stable, so once the load goes down, the taper can be held for a longer time and motor abilities can continue to be developed over the season. Digestible?
Please note that this is on the paper. Realization of this plan was hi-jacked by mis-understanding and lack of real co-operation between me and the head coach who was accustomed working alone, without s/c coach. It would be easy for me to test this if I was a head coach (maybe in far future in some sport) but for now I think I cannot work on my full potential and rather adapt from day to day and what is left in the athletes after team practices… This is the curse of s/c coaches, along with not getting medals too.