The cadence optimizer doesn’t impact the performance of the workout at all!
The Cadence Optimizer simply looks at your historical relationship between Power & Cadence and makes assumptions about where your optimal cadence should be, given a certain target power. You’ll generally notice that as the power target increases, the recommended cadence also increases, and vice versa. If your interval is well below LTP, it doesn’t make sense to keep pealing near 100 rpm… in fact, that’s actually more inefficient!
Hope this makes sense!