It is common among several types of shooters at high proficiency. Most of my pistols have a black rear and some type of front sight that is brighter. That might be fiber optic, Tritium or some combo of light color and a fiber optic or Tritium. I have my iron sighted rifle the same way, black rear and Tritium front. Bullseye shooters before there was fiber optic would have black rear sights and gold bars inset in the front ramped blades, or colored inserts.
Whatever you use, the goal is to have the front sight be easy to pick up fast and the rear sight to not be distracting. Does not matter if for speed, accuracy or both, same principles apply to both. The only departure for the speed or combat shooters is that at some distance and closer, you don't see the sights...they are still there, and lined up, but when the skill level passes a certain level, the mind no longer needs to settle the sight picture and the shooter fires as soon as the "acceptable" sight picture occurs without conscious thought. That too is aided by not having anything other than a black rear sight.