sure, sounds like you MIGHT be at upper end of gains from pure sweet spot work. Your power at threshold is a balance of aerobic capacity and anaerobic capacity. My best gains in sweet spot happen when I’m doing outside riding and naturally working the anaerobic system. However I don’t have the strongest anaerobic system, so thats not too surprising. You might be one of those that would benefit from some vo2/anaerobic work during base.
If you know what threshold feels like, it would be more interesting to compare 5-min power from ramp test to your self estimated FTP (by feel from SS and/or threshold). Doing that, I’ve seen my fractional utilization as high as 90% (FTP / vo2max-5min-ramp) which makes me an outlier. The normal range is 78-85%. Right now I’m around 85% and doing some vo2 work every week to complement my current focus on sweet spot.
More info from Coach Chad: