I haven't run a prewash in years.
My 1993 Bosch countertop dishwasher used enough water, heat and pressure to probably qualify as a Hurricane in a Box. A 20-minute wash got everything clean. Plus, it ran three rinses.
My current, modern dishwasher... I think it prewashed once. Besides, I tend to use a cycle without prewash anyway and add an extra rinse.