“It's a dummy solo I laid down – I was supposed to put down a real one later. But I never got time”: Ozzy Osbourne's Diary of a Madman is a landmark guitar album, but some of its final parts made Randy Rhoads “cringe”

Ozzy Osbourne (left) and Randy Rhoads perform at Nassau Coliseum in Uniondale, New York on August 14, 1981.

Looking back on the rock world 45, 50, or 60 years ago, it's remarkable how prolific acts of every sonic persuasion were expected to be.

There are more examples than can be easily listed here of bands or solo artists releasing, in their early days, albums every 9-10 months; a clip that's almost unthinkable now.