Last month I was able to visit the farm of Jose Luis Prieto in Pinar del Rio, Cuba. I learned a lot about the leaf called Medio Tempo. It seems this leaf has always been around, and as Cuban cigar smokers we have smoked it in the past.
It can only be identified by experts in the field. In identifying the leaf, it is not from the middle of the plant as medio would imply, but from the top, as in the ligero portion of the plant, but not all plants will produce medio tempo.
This is the reason that Cohiba Behike must be 52 ring gauge or larger, because they must contain this extra leaf.Imagine 5 leaves rolled into the cigar.