I'm not sure how those work. They sound more mechanical (like old school speedometers) that will run faster or slower based on speed. The Pioneer speedo would be amiss if it calculated time by how fast or hard the unit ran. Unless, of course, it is not measuring actual time but the intensity of engine use, thereby telling us how hard the engine oil is being taxed.Tractor hour meters are set to full PTO rpms, so, yes, running at 1/2 PTO speed will slow the clock by 1/2.
Honda may have put it to a hour meter to make it simple for us to track without trying to understand their computerized calculation of engine rpm, acceleration, load, engine temperature, ambient temperature etc. that is taking place before it reaches the hour meter as a number for us to measure our next oil change by.
I'm going to have to test this topic. It intrigues me.