This is a great drill to get used to running a full table and to loosen up your arm at the after working on stroke drills. All the pots are relatively easy and the focus is keeping the cue ball off the rail and playing area shape on several balls at once. It’s good practice for open 8 ball racks when you just need to clear an easy table and not miss.

Variations
Beginner
If all 15 balls is too difficult, use less balls. Start with 3-5 between the foot-spot and the short rail. Use an amount that you can consistently run at least half of.
Intermediate
At the intermediate level just running all 15 is good practice to work on consistency in both shape and ball pocketing. Move on to more difficult versions when this becomes routine.
Try to run them from top to bottom (in this diagram, starting from the 11 and working your way to the 1). You can shoot them in a different order, but try to always play shape on the ball closest to the side you started on.
Run only solids or stripes. Pot the 8 and then run the other group.
Advanced
Keep the cue ball on one side of the table.
Run the line in order, reset whenever you get out of line.
Run the line in order using only one side of the table.
Make sure the balls in the middle of the table pot to the corner pockets when you set the drill up. Run the table only using corner pockets.
Tips
Focus on getting on the correct side of each shot to play shape on the next without running into other balls.
The surest way to mess this drill up is to leave yourself frozen to the rail. On every shot try to leave the cue ball about one diamond away from the rail.