For folks having a problem with the One Pocket break, this may help a little. When i first started playing OP 'old timers' said you will learn to break good after you break 1,000 times. (BTW I am 78.) So I decided to study the rack and this is what I found on the standard break.
If on the break the corner ball leaks to the opponents side, the problem is not with the placement of the cue ball. The problem is with the rack. When breaking from the right side of the rack, I make sure the 2nd and 3rd balls on the left side of the rack are frozen to each other. If they are not frozen, the 2nd ball sends its energy to the balls on the right side and the end ball leaks out. These are the only two balls I pay attention to on the break. Let me know if it works for you.
PS. I place the cue ball approximately 5 inches from the right long rail on the head string and use left English.
If on the break the corner ball leaks to the opponents side, the problem is not with the placement of the cue ball. The problem is with the rack. When breaking from the right side of the rack, I make sure the 2nd and 3rd balls on the left side of the rack are frozen to each other. If they are not frozen, the 2nd ball sends its energy to the balls on the right side and the end ball leaks out. These are the only two balls I pay attention to on the break. Let me know if it works for you.
PS. I place the cue ball approximately 5 inches from the right long rail on the head string and use left English.