Have to agree that some of the things mentioned about Paul's ability to write a song in an hour or two is good and it's bad. It's good cause it proves that he is an incredible craftsman of song. It's bad because he get some material (a few songs) like on Driving Rain that is sloppy and poorly written. I'd say the same for a few songs (few) like on Flaming Pie.
I think Paul uses the Beatles work ethic (finish it up quickly) as an excuse not to really work to his fullest potential and slag off working on a song. That's a sense of laziness and loafing that i can do without. Like "I really love you" on flaming pie, I want your heart baby pipin' on a plate...or i need your love like a bird or a bear needs a break" - that's just laziness and it may be ok when you are collaborarting with a Lennon (who adds some bits that are genius) but i think it's kind of weak when he should focus and complete the material and not slag it off by saying the Beatles wrote hits in 10 minutes.
Paul has that nostalgia for writing quickly because of writing with John. Paul has always missed writing with John and has said so. John never admitted missing collaborating with Paul. As an artist one receives art from "outside". It comes in when the channels are clear. Sometimes they are not clear. Sometimes they are jammed. One's best work is given to you as a gift, sometimes at odd times as Yesterday came to Paul in his sleep. It may come out quickly in one piece- complete and beautiful. Other times it is a struggle and an artist notices that a piece of work is not very good or worse! Being creative is a blessing and a curse. It's also ingrained in your soul. The muze is fickle.