Looking at the TR workouts and doing them outdoors occasionally, I have noticed that for most of the rides with intensity that I know of (such as Sweet Spot, VO2 max, etc) the intervals and overall duration are the same indoors vs outdoors. However, when looking at the “endurance” category, there are some marked discrepancies. For instance, Koip outdoors is 50% longer than Koip indoors, same thing for Longfellow, but then for Vogelsang the time is the same.
Can someone explain this? I would intuitively agree that a workout indoors is more time efficient than a workout outdoors, but that would just be my intuition. Are these discrepancies data-backed or science-backed?