I believe Terry is referring to the 200m, come from behind final. Katie is taking a consistent 39 strokes (that includes 1 for the flip) on each 50m. Surprisingly, the last 50m, she dropped 2 strokes to 37 while digging deep, while other swimmers added two strokes, maybe more. Quite amazing.
Katie has a significant wall push which I estimate at 8m, so 42m stroked. 5'11 or 180.4cm in height, at 39 strokes stroke length = 1.077m, 37 strokes stroke length = 1.135m. This puts Katie at 60% and 63% respectively, stroke length to height or SL/height. Given her 5'11" frame, this is not a short stroke length, but an effective range that worked for her. Katie's range is right in the middle, above middle of what we (TI) refer to as the "Green Zone".
In the 800m, it sure looks to be the same pattern, 39 strokes consistent until the last 50m, 37 strokes.
The 1500m is hard to tell, camera kept panning to the audience, but I count 39 strokes as well, maybe a 40. But she didn't drop 2 strokes on the last 50m probably since she had a solid lead over the entire field.
I certainly agree with the narrative from Michael Joyner (and Terry): Ledecky had among the most remarkable endurance performances ever, and her best years are yet to come.