Barbara - yes, the boom-chuck-a works, too, on slower songs/tunes. I know a fine bluegrass mandolin who is adamant that the guitar should go boom-chuck - he says the backstroke "a" throws off the lead player's rhythm, and doesn't give the true bluegrass sound.

I've found when trying to play with a hot banjo or mandolin player that I don't have time to get a backstroke in - it's just too fast!

The question the beginner was asking, however, is why not do two single notes instead of the bass and chord ?