My problem with that is it seems to presume John rose to the level of IATW on a regular basis before he wrote/recorded IATW. In fact I'd say he'd only written a handful of songs as good as IATW before that.
Well, he was arguably at his peak before that. They all were, I think. 'Norwegian Wood', 'Nowhere Man', 'In My Life', 'Rain', 'Tomorrow Never Knows', 'She Said She Said', 'A Day In The Life', 'Lucy In The Sky With Diamonds', 'Strawberry Fields Forever' etc. You may not like some of those songs, but you can't deny their influence. Late '65 - '67 was a very creative period for The Beatles, including John.