David Bennett undertakes quite detailed analysis of just how common this chord progression is used:

The minor key table posted in the Circle of 5ths thread allowed me to at least partially understand what David Bennett is talking about.

At clock postion 9 (Cm) 6-7-1 is Ab-Bb-C

I wonder if other minor 6-7-1 progressions are as musically pleasing.
Bb-C-D (clock position 11) for example.

Thanks for posting.