First takes are fine, but it's nice to have played the song at least once before you're in the studio, or at least heard it! Dylan has written songs while the recording band sits around playing cards, but he has a big recording budget. On the Moontan album, the bass player and second guitarist didn't have a chance to learn the songs before recording began, so Evan and I played them alone---to get the basic rhythm tracks, and all other parts (and vocals) were overdubbed. Evan plugged his Telecaster into a Fender blackface Super Reverb, not his normal amp (a Deluxe Reverb, many player's favorite). The engineer put the amp in an isolation closet, and Evan turned it up to 10. If you've heard a Super (Stevie Ray Vaughan's choice of amp), you know how loud that is!
Speaking of Merle Travis, one song on Moontan is entitled "Shootin' The Merle", an instrumental tribute to the man. The album is half instrumental, half vocal, all Evan.