Although SS is not mentioned there, Marcus Baker has decent amount of time in Z4. Maybe it is time for AI FTP detection? Or if you can’t use it because recent detection, you have to simply override AT by choosing your own SS workouts (a la Polar Bear, Gibraltar, Pendleton). Sustained power SS workouts are fun
Meaningless in that almost nobody achieves a PL>10 and so it doesn’t make much sense to make comparisons or distinctions up there.
The PLs in a sense represent a bell-curve of fitness in each particular energy system for a given FTP. I believe 4ish is meant to be roughly the population mean which allows you to be strong in one category (eg, VO2 with a PL > 6), but relatively weak in another (eg, SS with a PL <= 3). Once you raise one of your PL > 10 you’ve essentially walked off the edge of the distribution to a point where there isn’t enough data to (statistically) support added benefit.
One way to address this would be to create a whole slew of workouts in the 10-20 range. To what end, though?!? Alternatively TR’s preference is to raise your FTP, thus lowering your PL back to a more statistically supported area of the curve.
Another way to think about this… what if you earnestly fail a 1.0 sweetspot workout over and over? Clearly your FTP is set to high. It’s not like there are -2.0 workouts you can try next, but even if there were do you really want to quibble about whether you’re really -2.0 or -4.0?
And @svens is also correct There is a different, more involved kind of magic happening with AI FTP Detection. Think of Progression Levels as a real-time representation of your fitness and ability to express your FTP across each training zone.
I see you’re not currently following a TR training plan, but if you were, your Progression Levels would work in tandem with Adaptive Training to serve you the necessary adaptations for future workouts.