Paul wanted his vocals for Oh! Darling to be rough and raw, "as though I'd been performing it on stage all week." To accomplish this, he sang the song in studio every day for a week. John later commented that he should have sung the song himself as it was more his style.
"I came into the studios early every day for a week to sing it by myself because at first my voice was too clear. I wanted it to sound as though I'd been performing it on stage all week." - Paul