Dear @DanK, thank you for the question. Thanks @Marjaana for chiming in.
We think that indeed the training program is rising your “fitness” to a point where it plateaus because of the time constraints. You might need to switch to a higher-volume plan to see “fitness” increasing beyond the first ramp. You might want also to try raising the min-max training hours, currently set at 8-12.
However, one small observation. We know that it reads “fitness” but it’s not the same as “performance capacity”, or level. Arguably, you can keep improving even if your “fitness” is steady. In fact, that “fitness”, is indicative of the training load that you can sustain “chronically”, but there are so many aspects of an athletic preparation that can be improved regardless of the training load (especially in disciplines where power output is meant to be highly variable and where there are relevant technical components).
Working on all the aspects of the power profile, for example, might lead to improvements in the performance, without necessarily imply additional training load. By working on the interplay between frequency/duration/intensity of the sessions, Athletica is trying to create a 360°-degree preparation, with the time allowed by the specific training plan.
Please keep us posted on your experience with this training plan, especially if you try to switch to plans with higher volumes or you try to change time-ranges. 