Hello Joe, Hey great question. I especially like how, banjo ben addressed this topic in his Allan Munde series āwhere to put your fingersā. It helps to start-out with āsafeā rolls that you know have the correct notes/measure. Itās a great lesson for expanding backup and also banjo bens vamping lessons canāt be ignored .
My own personal experience only; (take it as a grain of salt) but every song will have a chord structure and by āvampingā through the song, youāll be moving your fingers for the most part, where they need to be and can be vamped or rolled for the most part on a basic-level. A good example for rolling tricks might be the Tony Wray backup series. Youāll notice that those licks essentially force your hand into a chord position. Then when you want to add spice, you can through a roll or two in there, especially adding licks & tricks at the D-turn around or during times when the singer or soloist pauses. For sure, as you said, it takes work to roll and make the beats come out right, I think that comes with experience. Starting out with āsafeā rolls is a great way to start (e.g. square-rolls, alternating-thumb) but then experiment with more complex transitions. @banjoben has outstanding lessons on those juicy passing rolls, turnaround rolls and even intro rolls. I guess what got me started on backup, was playing as a youth in our monthly āhoe-downā (incidentally where I met my future wife ). There, I would spend 98% of the evening doing nothing BUT backup. When it became my turn to solo, I got so excited! Absent an actual partner to play backup to, itās always worked for me to just backup someone playing a solo on a recording. Any number of banjo ben lesson demos could be played to do exactly that. My humble opinion.
Hereās the thing about backup though. Youāll never play the same backup twice even in the same song. Earl Scruggs might revert to a tear-drop type back-up on the 2nd verse, when he did something different on the 1st verse, etcā¦ Otherwise, your backup will become dull & boring. The important thing, is to have the basic tools to lay in the back-up to express the mood of the song. Starting with vamping over the chord structure, then adding licks & rolls as you feel comfortable and as it fit. It seems to me, that banjobenās backup lessons are purposely presented exactly for this purpose. To give us the tools (rolls, licks, tricks, vamping structure) to use, and then we have to be able to think for ourselves to apply it which really, is inferred as part of the lesson. In the end, that is exactly what we need to do or weāll be doomed to read Tablature the rest of our lives. There is nothing wrong with tabbing out backup of course, its commendable. But youāll eventually find yourself looking just for chord structure and playing from the heart to assist the soloist. Anyway, this is my own personal experience and others will have their own ideas which could be better. The most important thing? Have fun and HAPPY PICKING!