However, you are striking a balance between too many levels and not the correct ones.
I think you should make up divisions of 1/3 and 1/6 note them and then see if they strike.
Does CL turn at these points? If so then use them, and discard the power of 2 divisions that are too close to your power of 3 divisions.
You are working with the resonance, or harmony of the move.
Where does it vibrate to (and when)?
Bottom-line is you want to "tune-into" the music of these oscillations that are profitable to you and the time frame (frequency) you are trading. If you only want one trade a day, you may find that the power of 2 works better, and for 5 trades perhaps the power of 3 level works better.
At first be open and check both.
See what history shows
select and choose what it right for you.
Gann tracked each contract on its own, for example Sept soybeans, and over many years. So he knew the high of Sept soybeans each year and applied it to trading Sept soybeans.
(It may be that the contracts for agriculture products have enough volume to trade for most of the year without switching contracts. (He would close out his Sept contracts at the end of Aug and wait out the month of Sept, starting to trade again in October).
For our example the difference is small - 20.20 to 20.09 and probably doesn't matter.
Try working with both and see which gives better results.
If looking at the more esoteric concepts then the price of the high would/could matter.
So for June it was 114.83 on 2 May and for July 115.27 for that high. (I may write an "aside" on number reduction and there I will explain how it could matter.)