One of the challenges to learning and playing bluegrass banjo is to learn correct technique so you can keep up with the fast tempos so many bluegrass songs have.
One of the tricks to playing consecutive 1/8 notes on a banjo is alternating your fingers. If you are playing 1/4 notes it's no problem to use the same finger twice in a row, but on a fast stream of 1/8 notes in an up tempo bluegrass song, using a different finger for each note is how it's accomplished.
The purpose of this banjo lesson is to help you know which finger to use when you have an option, and to explain what the best option is.
In Scruggs Style Bluegrass 3 finger technique when there is an option to use either the thumb or index finger to play a melody note, the thumb is the preferred finger to use, when available.
For instance in Scruggs Style the thumb often plays the 2nd string as long as you have not used the thumb on an 1/8 note just prior to needing to pick the 2nd string. In that case the thumb is not available and you would use the index finger.
In the examples below, see where the thumb is used and where I had to use the index to play a melody note because I had just used the thumb on an 1/8 note just prior to using the index.
Keep in mind, you do not have to alternate fingers if you are playing 1/4 notes.
Because the thumb is the preferred finger to use for melody notes in Scruggs Style, using the same finger consecutively for 1/4 notes is fair game when possible, and good technique. Not only that 1/4 notes are more often than not melody notes. There are exceptions to any technique but don't let the index finger drive the bus in Scruggs Style. The thumb leads the way.
See the examples below where the thumb is used for consecutive quarter notes and also where i it isn't. For instance I may have to play the first 1/4 note with the index because I had used the thumb on an 1/8th note just prior to using the index, but on the next 1/4 note I switch to thumb, which is better technique.
There are exceptions to any technique and if you think I can't play 1/8 notes with the same finger as fast as anyone, you're wrong. But my job is to teach you correct technique so you won't get tangled up and will develop the best rhythm and drive. You will be able to make your own technique exceptions when you are clear on the difference.
The bottom line, when playing the melody in 3 finger bluegrass Scruggs Style is don't let the index finger drive the bus. The thumb leads the way.
Thanks, Ross Nickerson