Brain growth work combined two previous fields and expanded on them. ADD-ADHD (Prefrontal cortex) and Hemispheric-synchronization (Corpus Callosum which is the bundle of nerve linking both hemisphere). In addition to that stimulated a broader area on top of the prefrontal cortex up to the limit of the frontal lobe.
So the Brain Growth Work focused more on stimulating a broader area and all the networks within indiscriminately, there was this idea in the description about testing brain fields results with it.
The Frontal lobe is broadly associated with higher cognitive functions, complex reasoning, it is a very human specificity and it’s also the latest part of the brain that forms in teenage and adult hood. It is involved in maturity and all. This is an area that is well studied in personality etc. So it was interesting to use brain growth for the curious. Not every single network in that area was as important and the networks associated to them would not be covered outside of the area (keep in mind that the brain of relatively decentralised and thinking is a global process).
Now, you can use the fields included in Brain Growth that I listed above, they will cover a good chunk of it or you can get more recent and advanced fields such as Manhattan method that cover many networks all other the brain to boost most of these abilities higher cognitive functions better.
As much as I personally liked Brain Growth Work, there is more than enough to compensate its loss.