Actually since doing that test I came across some information that backs up my experience.
The research suggest that the Hippocampus works best in this time period too in relation to learning new stuff and memory. The peak learning block is the first 7 minutes where you pick up most of the new information then there is a drop 7 minutes where maybe only one or two new ideas are learned then there is a rise again where the mind is "getting it" again... not as high as the first 7 minutes but much better than the preceding 7 minutes. At the end of this 7 minute cycle there is another drop which is even lower and almost no learning takes place. Instead of spending that 7 minutes in unproductive study take a break and you start the cycle over again afresh.
I'm sorry I don't know the actual source of the research. It came to me from a research source I consider secondhand. However looking at the Accelerated Learning techniques and their recommendation based on their finding it makes sense.
Alex