I posted in another thread about tuning a piano. I can tune a piano - it isn't crazy hard. However, my tuning won't stay in tune, because I inadvertently leave a subtle twist in the pins themselves. I lack the feel to know when I'm twisting a pin vs. when I'm turning a pin. In other words, I leave unnecessary tension that (over time) gradually works itself out. My intuition tells me that a bike wheel would be similar.