In his video "Modern Electric Bass" Jaco Pastorius attributes his pitch accuracy and part of his tone to playing directly on top of the fret, even when using a fretted bass, rather than just behind it. This was the first I'd heard of this approach to left hand technique. It makes some sense, as I play a fretless Precision Bass in a jazz combo and I play (well.... try to play) exactly where the fret would be. This should transfer to a fretted instrument. When you play a fretted bass, does anyone play directly on the fret? If so, was this taught to you or did you figure it out for yourself.