The trouble with things like these is that humans are tricky as measuring devices. We can be quite good at noticing relative differences, but appallingly sucky at quantifying absolute values.
And a rider that FEEL that the bike is just ”right” may simply ride a little harder and become a little faster because of that. The actual difference in performance or efficiency may be minimal to insignificant. Rider contentedness, ”placebo” brings the improvement, not the actual, mechanical difference.