I tried once from a Paul Robeson recording to figure out what the time was to Shenandoah. I failed. Then I saw the music written out with bars of 3/4, 4/4/ and 2/4. Looking at it, I thought the "free" meolody was more satisfying than forcing standard bars on the song. Robeson sang it this way. Leon Bibb's great CD "Shenandoah" from 1997 does the same thing. Lots of rennaisance madrigals, and earlier music like chant had no bars. Forcing bars on them makes them sound mechanical.