Hi khallock. Real lighting novice here, just thought I'd share our recessed lights were installed today at 30" wall on-center, not 24". We will have upper cabinets. My GC feels 30" is better for light diffusion, including of the uppers and path through the kitchen. We will have good quality task lighting in the form of under-cabinet lighting as yourself.

Recessed lights should be based on location of countertop edge. In reflected ceiling plan, the light should go no further from wall than the edge of the counter. The reason being, you don't want your head to get in the way and create shadows on what you are doing at the counter.