The song of the week is 'All The Good Times Are Past And Gone' in the key of A. This song is traditionally played in 3/4 (a.k.a., 'Waltz') time.
The chord progression for 'All The Good Times Are Past and Gone' is:
[Progression V6 on the 'Basic Chord Progressions' handout. Probably the most well-known song in 3/4 time that uses this same progression is 'Amazing Grace'.]
In the key of A: 1 = A; 4 = D; 5 = E.
With a capo on the 2nd fret, the chord shapes become: 1 = G; 4 = C; 5 = D.
Notice that on the Flatt and Scruggs recording of 'All The Good Times' (see the youtube link below), and extra measure of the '1' chord is played at the end of each of the breaks before the vocal comes in. When playing this song at the jam, this may or may not happen, so be prepared for either scenario. Also be prepared for the possibility that more than one measure of the '1' chord may be added to the end of some of the breaks before the vocal comes in. The safest thing to do here is to just keep on hitting the root note of the chord (on bass and guitar) at the beginning of each of these additional measures of the '1' chord so as to guarantee that you will be playing the root note of the chord at the time when the progression starts over from the beginning.
Flatt and Scruggs, key of A
To say that a song is played in 3/4 time means that there are 3 beats per measure in the song. On guitar, when playing rhythm, one measure will consist of 'boom-chuck-chuck', i.e., 'bassnote-strum-strum', rather than the more common rhythm for bluegrass songs of 'boom-chuck-boom-chuck'. Notice that this means that in 3/4 time it takes two measures, instead of one, to get through a cycle of root-5 (alternating bass) on guitar (and on bass, if you are playing only one note per measure). For this reason, it can be useful to think of the chord progression in groups of two measures.
The root note of each chord is simply the note that has the same letter name as the chord. The '5' of the chord is the 5th scale degree of the major scale that has the same letter name as the chord. The first five scale degrees of the A major scale are A, B, C#, D, and E, so when playing 'root-5' over an A chord, this means that you are alternating between an A and an E note.
There are six major (and six minor) chords for which identifying the '5' involves nothing more than counting up the musical alphabet, without having to worry about sharps or flats. The six are: A, C, D, E, F, and G. So, the 5 of 'C' (counting C is as '1') is G (1,2,3,4,5: C,D,E,F,G), the 5 of D is 'A', the 5 of E is 'B', the 5 of F is 'C', and the 5 of G is 'D'.
Taking the progression two measures at a time, the first two measures allow one to play 'root-5' over the 1 chord, but the second group of two measures (i.e., the third and fourth measures) allow one to play only the root note of the chords called for there, because the second of these two measures has a different chord than what the first of these two measures does. So, this scenario is similar to what happens in the non-3/4 time songs we play at the jam in which a single measure is split between two chords (e.g., the 7th measure of each of the parts of Boil The Cabbage Down and Soldier's Joy, or the 4th measure of each of the parts of Shortnin' Bread and the B-Part of Cripple Creek.)
The second line of the progression for All The Good Times allows one to play root-5 over the 1 chord and then over the 5 chord. Notice that this means that two root notes over the 1 chord end up being played back to back, one in the last measure of the first line, and one in the first measure of the second line, since the first line of the progression ended with the 1 chord, and there was only time to play the root note of the chord, but not the 5, because the third measure of the first line called for chord that was not the 1 chord.
When playing a 'vamp'/'chop' rhythm on mandolin, banjo, fiddle, or dobro, a measure of 3/4 time will consist of 'rest-chuck-chuck', which is the same as the guitar rhythm, just without the bass note at the beginning of the measure.
When playing a roll in 3/4 time on banjo, you will have time for a maximum of 6 plucked notes per measure (counted as '1 & 2 & 3 &'), rather than the usual maximum of 8 notes per measure ('1 e & a 2 e & a'), Considered in relation to a roll pattern consisting of 8 notes, this usually involves omitting either the last two notes of the roll, or in some cases, the 5th and 6th notes of the roll, or the 3rd and 4th notes of the roll. If approaching playing in 3/4 time from his angle, make sure that the 3/4 time rolls you create by dropping notes from the standard 8 note rolls don't result in the need to play two 8th notes back to back with the same finger of your picking hand.
There are many standard (common time: 4/4, or cut common time 2/2) licks on banjo, as well as on the other bluegrass instruments, that have 3/4 time equivalents. The 3/4 time versions of these licks in many cases can be derived from the common time or cut common time lick by omitting a quarter of a measure's worth of the least essential notes of the lick.