Hmmm...just had to make this comparison:
The Ryodan wouldn't have been such a powerful organization had each of its members worked alone; it was because they came together as group that they were more efficient.
Individually, each of the Spiders is an expert in their field. However, they might not thrive so well if they had to work in a different field; thus, their diverse skills complement each others' weaknesses.
Kuroro himself also believes in the importance of working as a group. When he says that his life is unimportant compared to the Spider's survival, he understands that if one leg of the Spider dies, its not as important as when the Spider lives--because their power does not lie in an individual, but in their group as a whole...
And...a Civil War general once said of his army,"Some of us will die...many of us must make the sacrifice...but all of us will not die." This goes for the Ryodan as well--perhaps some people had to sacrifice, but that would assure the entire Ryodan wouldn't die.
Because of this, the Ryodan can be compared to a 'corporation', (or really, an underground criminal corporation...). In this case, the CEO would Kuroro, but then he'd be much better than the CEOs of our corporations (since most CEOs are all selfish and care too much about ranks and position...).
He believes in the wellbeing of Ryodan as a whole, and not necessarily his life. How many CEOs out there are willing to sacrifice something of their own so that their employees can survive? (Some...but not many...)
In a corporation, there is always a department called R&D, otherwise known as research and development. Among the Ryodan, Pakunoda, Shalnark, and Feitan are responsible for R&D. Pakunoda probes into others' minds, thus, does research and Feitan tortures people for information.
Without the research, a corporation would be going off into random directions, not achieving any goals. For the Ryodan, they too need info first, so that when they carry out their goals, the lives of the Ryodan won't be put into danger.
Then, after the research is done, there needs to be strategies made--obviously--mostly taken care of by danchou and Shalnark.
When it is time for these actions to be carried out, Ubogin, Nobunaga, Phinks, and Feitan (he actually has more than one job in this corporation) are the one's carry out the actions--the actual workforce.
Unlike in an actual corporation, the Ryodan has about the same amount of information gatherers as action takers, but because all of the Ryodan's actions need to be taken with caution, the information gathered is very important.
Thus, as a whole, the Ryodan have turned into an efficient corporation.