I'm not sure where to provide accurate proof, but with regards to the KGB under Stalin, the impetus was knowing that you couldn't trust anyone else in your organization. Everyone reported to someone about something, so even if you were the head of the KGB, you might have an underling who is reporting directly to the Party Secretary.

Basically, the idea is more or less that the organization is self-regulating. No one can really go rogue or accrue too much power for themselves, since they can't trust anyone else not to report their behaviour to someone else. And since the likely punishment would be exile/death, it wasn't worth the risk. And with Stalin's fondness for purging 'threats', it was certainly a risk of trying to do anything that could be seen as collecting power for yourself.

Ultimately though, for a lot of these organizations, its a sort of cult of personality that keeps a lot of them in line. The SS clearly believed in their leadership, and their leaders believed in the cause and Hitler. So even with a degree of autonomy that the leadership had, their ranks were still filled with 'true believers'. And while Himmler likely had an interest in taking Hitler's spot after his suicide, it seems unlikely he had such ambitions while the Fuhrer was still alive.

TL;DR: Either keep them in line through paranoia and risk of death, or ensure the leadership is completely devoted to the cause.