To rd600,
Circle of 4ths is important in your learnings. One thing it does is helps you in your quest to play in every key (because it covers all 12 keys). It also shows relationship between the different keys. I think that it is a good tool for musicians (especially beginners) to use. I practice the circle often, even adding tritones in Lh. I use to have trouble figuring out chords in certain keys, but thanks to the circle, I can go straight to them, but just have to invert some or most of them. Be blessed and keep on keepin on!
B3Maniac.