Kicking, Punching, Trapping, Grappling and understanding the weapon. These are the 5 aspects of combat that need to be understood. The question then becomes how do I use these in long medium and close ranges.
This is where the misconception of Jeet Kune Do being a mixture of arts is derived. People commonly believe that each one of these aspects should be researched on its own. For kicking and punching, people commonly study Muay Thai, for trapping they study Wing Chun, for Grappling they study Jiu Jitsu, and for weapon they study Kali.
When in reality Jeet Kune Do is an art that encompasses all these different aspects of combat. If a person is studying Muay Thai on Monday, Wing Chun on Tuesday, Jiu Jitsu on Wednesday, and Kali on Thursday, how are they expected to perform any of those arts at a high enough level. One becomes a "jack of all trades but master of none."