I think the ghost is a great way to become a better player and a fun way to practice. When you get up to the 6-ball ghost start also keeping track of if you parked the Q-ball in the middle of the table. But don't count it as a loss if you don't. I believe you still need an hour or so of position and pocketing drills a day too.
When you get so you can beat the 6-ball ghost a fair percentage of the time, set up Missisispi 9-ball and see if you can beat that ghost. Good luck with that

. Johnnyt