Interesting to see this resurrected. Our philosophy with my band has been to learn parts outside of band rehearsal and it works well. We are a 2 guitar band, so we guitarists will decide amongst ourselves who plays what. We'll share stuff we found on the Internet on playing the song.

We rehearse 2 hours a week, so the rehearsal time is limited. The other problem with learning or teaching a song during band rehearsal is some people are just sitting around then, feeling like their time is wasted.