It takes 4 things to standardize pockets, the pocket openings, the pocket angles, the pocket down angles, and the slate shelf. The bottom line is "Fair pockets", as in not hard, and not easy! A pocket opening of 4" with parallel pocket facings is a smaller target, not a tighter pocket. With pockets cut like that, the ball is either in or out, but won't hang a ball in the pocket, that's not tight, it's just a small target. I changed a Diamond 9ft ProAm table up at the Golden Fleece pool room in Washington state to 3 7/8th's corner pockets, and 4 3/8th's side pockets, but I DIDN'T change the pocket angles to face each other, I left them at the 51 degree funnel openings, THAT'S a tight table. It was easy at first, until the cloth broke in

NOW..it's just a one pocket table, because it's to hard to play 9ball on, god would have a hard time running a rack of 9ball on this table

so when you'all say tight pockets, it all depends on the conditions, as very few tables are tightened the same, sometimes even by the same person doing the work. I can't tell you how many times I've seen tight pocket tables...that no 2 corner pockets are the same...on the same table!
Glen