Lucky adapted the organization
put in place by Maranzano, who
was too greedy even for a boss.
Back in the 1930s, after doing his part to end the war between Joe "The Boss" Masseria and Salvatore Maranzano, "Lucky" Luciano Americanized the Five Family set-up put in place by Maranzano; it is from Maranzano that we got the boss - underboss - consiglieri - capo - soldier pyramid structure, which self-described historian Maranzano based on the way the Roman Legionnaires had been organized.
The problem was that Maranzano had added an additional position, for himself: Boss of Bosses. It was his doom. Lucky did away with that title after doing away with Maranzano. It was agreed no one man would ever hold that title, though over the years, some bosses seemed to fit the bill on an informal basis nevertheless. I'd say Carlo Gambino was definitely one of them.