It's not good for sport fighting like MMA or the like.
For self-defense it is useful.
Bruce Lee gave it up as it did not work as well as boxing with footwork from fencing.
Lee also used kicks from Tae Kwon Do.
According to Dan Inosanto in a video he said Bruce Lee changed techniques even monthly in his system.
As did Dan later on bringing more Kali into his interpretation of Jeet kune do.
I believe originally Bruce Lee used more Thai boxing & Savate in his system as far as kicking goes, certainly in his Original programme in Gung Fu Thai kickboxing was very evident.
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