Yes, Glenn, when the leader is singing, the crew is resting. Then when the crew is singing, there are two pulls. If the chorus is written down as 2 measures, then the pulls happen on the start of each measure. If written as 4 measures, the pulls come at the start of measures 1 and 3.

"Blood Red Roses" is a weird example because it was sort of reinvented. The movie form (which spawned the folk scene form) is not authentic. If you can find the authentic version of the song recorded by Alan Lomax in the Bahamas in 1935 ("Come down you bunch of roses"), you can hear that the measures are even and the downbeats -- the pulls -- are quite obvious.