That's true. Superman could well appear to be the better detective because of how fast he thinks and his senses. On the practical level, that will just result in the same stories we already complain about where Batman is at peak or better and Superman is way watered down. But we get the emotional satisfaction of saying, "If Superman were also operating at peak, if the writer wasn't cheating, Superman would smoke Batman." That's the situation we already have because there are, at last I checked, still rare situations where Superman thinks that fast. Of course, it's never going to be in a story Batman is in.