umm if u really want to think about all of this then figure out the specific gear ratios ur tranny is using and do the math, i bet that the gear ratios places all of these speeds at about the same rpm, probably not done on purpose or nething just ended up being the most efficient way of gearing ur particular engine, my crx hf d15b6 engine literally holds the same level of acceleration of rpms and speed in 2nd gear from 30 mph-50mph as the rpms kinda weird watching ur tach go up exactly the same as ur speedo... just weird coincidences i guess.