The potassium argon dating method is a reliable method for dating samples. However, it is better used for dating extremely old samples which it is able to date reliably because of its long half-life. For regular dating, you can always use carbon 14 which provides an authentic result. The potassium argon method is the only isotope method used to date prehistoric remains.
The other isotopes don’t have half-lives that extend into that era making them valuable assets to the geologists. Knowing this will help you understand the different concepts of radioactive dating better and date samples and geological remains more accurately.