Being able to play positions, playing in other keys on the same harmonica, is a fairly standard requirement for the blues harp player.  Most players use just 1st, 2nd and 3rd posiion. I have created some unusal study songs that focus on rarer positions, like 5th and 6th, which are seldom heard in traditional blues, but have a value for minor blues.  3rd position is often thought of as minor, but here I do have one for minor blues and another for standard blues.  The 1st position study song, 1-P Blues, is great study of the entire 10-hole range of the harmonica which is unusual because of how seldom the middle range is ever used in this position.