Marlon also is spotlighted on Corner of the Sky. Interesting that he and Tito weren't utilized much in the studio. The background vocals sound fuller though than just 3 singers, wonder if the added some studio singers

While these certainly don't amount to full shared leads over a period of time, I do find these to be interesting shared group leads:

Too many fish in the sea - all four girls on the chorus
Breathtaking Guy - all three sups on chorus

Also it's interesting to note the uneven amount of shared vocals in a group. Otis has significantly less lead lines songs like Psychedelic Shack and I Can't Get Next To You than the rest of the group.