During that comeback era Rijkaard taught his players, and explained to the media, that free kicks, throw-ins and corners were to be taken as quickly as possible, as often as possible.
Literally, instantaneously. Walk up to them. Take them.
He argued that if this became a habit, then Barcelona's players would always be seeking an advantage, would always be sharp and ready to catch their opponents out.
But the Dutchman also pointed out that some rivals would specifically be undone by this tactic, that it would consistently win Barcelona matches.
Graeme Souness explained what the mighty Bob Paisley taught Liverpool about this practice when they dominated England and Europe. The tactic at Anfield, which was a direct antecedent of what Rijkaard preached, was called: "find the dope."
The idea was that at any break in the play just before half-time or full-time, some rival would take a breather -- either physical or mental -- around a throw-in or a set play. However fiercely they'd been marking, pressing or putting their tactical plan into action, there'd be a momentary drop in concentration.
The idea for Paisley's Liverpool and Rijkaard's Barcelona was that every one of their own players would not only be waiting for that, but expecting it and prepared to ruthlessly take advantage.
If you want to see this concept brilliantly executed go to the free kick winner which Lionel Messi (ironically) scored against Atleti (ironically) in the 2011-12 season under Guardiola.
Lionel Messi came off injured in the second half.