One advantage of thinking in rolls (and licks) is that each one of them last for the same length of time.
This makes it very easy to switch between the two.
When learning to play a particular roll, the first thing you do is try to play the entire eight notes evenly.
Once you get that, the next step is to go evenly to the next roll.
Then you try to switch chords between rolls and add lefthand effects in the middle of rolls
all the while trying to keep the music flowing evenly.
The next step to practice is switching between the rolls themselves between measures.
It takes practice.
Here is one version of Bile Dem Cabbage Down done with a panoply of rolls.
This has just been an introduction to rolls.
It shows you the basics of how to do them and more importantly, how to think about them so you can begin to insert the melody of a song into them.
The next step is to begin using them yourself.
Check out my section on sheet music for some basic tabs to songs,
or get Pete Wernick's Bluegrass Songbook
or if you can read music, play through song books.
That concludes this brief intro to bluegrass rolls on the 5-string banjo in G-tuning