Brain Coherence is when both sides run in one EEG, synchronized and working together. Do you realize how many working methods exist, to reach this state for limited time to achieve the benefits? There is hemisync music, special pictures to view, deeksha, meditations and simple methods like focus on your breath.
All of them bring down the left hemisphere from its high beta frequency and sync it with the lower frequencies of your right side. Biological the corpus callosum have not enough nerves to connect both sides, but they will grow if you step into coherence again and again. In history there was no better idea as this disconnect and higher frequency range for left side only. What result to a backdoor, the given opportunity to fix this separation in biology. The result is a coherent mind that show the Maxwell Cade EEG named awakened mind.
If you like it, just get it by some diligence. You have to prove that you want to turn back to coherence or it will fall back in separation very fast. The EEG is not carved in stone, there is biological basic behind it.