.....Just to add to DrinkandDestroy's notes on the fine details of Leone's work:
I love the way that Indio sends Manco off to Santa Cruz with Blacky, Chico and Paco who if you remember are who Groggy turns up with. In short, they are Groggy's men; he doesn't send any of his own crew.
I always got the feeling that Groggy is eyeing the throne and is from the start a bit disrespectful of Indio and a bit overfamiliar; laughing at Sancho Perez' imprisonment and saying quite deliberately that "a man who gets caught doesn't deserve respect eh?" in the full knowledge that Indio himself has spent some recent time in prison.
I think Indio realises that Groggy is also a danger so by casually sending Groggy's men off he weakens Groggy's powerbase...kills 2 birds with 1 stone (or 3 in this case).
I never caught that detail myself, cool.

Indio seems more of an evil genius with each passing view.