Why would there be such a need to hold special tests to skip multiple ranks?
Off the top of my head: 1) Say you have a KKW 1st Dan, & changed schools & ranked up in say the ITF. then you want to come back to the KKW after a number of years. 2) You were told that you had legit KKW rank past 1st Dan & it was found that your instructor never sent it in. You think you're a KKW 4th Dan, but you only have a 1st Dan.
Sorry, but "getting screwed" in the past was my 1st thought as to why someone might benefit from a special test like this.