If Kogoro actually puts his head into the game, he will be scarily accurate and swift. If he was motivated enough in every case he seemed to come across, he wouldn't NEED Conan to solve his cases, and probably would be just as famous.
However, Gosho and whoever runs the anime decided to make Kogoro a complete Butt Monkey, which sucks, 'cause Kogoro is a good character. Therefore, the law dictates Kogoro will make a stupid, idiotic deduction, get knocked out and essentially be a puppet for Conan or require Conan to point out every single last stinkin' clue.