The best advice I was ever given regarding playing the ghost was offered by the late and great Jimmy Fusco. He spoke of the break and ball in hand version on 4 1/2" pockets, which were the norm when he and I had the discussion.
Jimmy offered that a typical amateur should start by playing races to three against the six ball ghost. Once they win five straight sets, they can move on to the seven ball ghost, but if they lose five sets in a row, they should drop down to playing the five ball ghost, and so on. One quickly learns where their proper level lies and can easily measure their progress. The process offers motivation for the player to advance as well as avoid falling back, which comes with pressure.
Stronger players, Jimmy said, should race to five against the ghost. Fargo 650-700 players tend to level out at the nine ball ghost, players in the Fargo 700s tend to level out against the ten ball ghost. Only an 800 player is likely to be the favorite against the eleven ball ghost, and anyone who beats the twelve ball ghost more than half the time is a serious threat to win a major championship. I recall that shortly before he won his US Open 9ball title in 2006, John Schmidt mentioned to me that he was winning most of the time against the twelve ball ghost.
I recall watching the legendary Dennis Orcullo at Derby City, in about 2019, gambling with a side-better that he could beat the ten ball ghost in a race to seven using "ten ball last" rules on a 4 1/4" pocket table. Dennis won the first few sets before the side-better pulled up.