Very interesting question. I'm going to have to pay more attention. This is an interesting interesting question.
30x23 == 35" , hard uphill
30x12 == 68" , level or slight uphill preparing for downshift
52x14 == 96" , slight downhill
42x15 == 76" , level
Similar question, would be "How do you use your gears?", do you stay on one chainring, or do you double shift a lot?