Your example says it all.... gig time as practice is something only a non-musician and/or someone who really doesn't understand practice would say. He gives air time to the idea of deliberate practice and then uses examples that show how that he doesn't get it. AT ALL. I can only assume he came up with the Beatles example and thought it was such a compelling story that he was determined not to let the facts get in the way. Ericsson goes over his criteria for what deliberate practice is.... and nightly gigs are not it in the least!

Read Ericsson and I'll be you will get disillusioned as did I.