During the setup process, the tecnician is striving for a balanced pattern which provides not just optimum engagement strength, but also offers longer gear life and reduced noise. The correct pattern is like an elongated oval that slightly favors the toe side of the ring gear on the drive face. Under power, the pattern "stretches" as load is applied equally across the gear teeth. Favoring the toe side helps ensure that the pattern doesn't run off the heel end under load, flirting with potential gear breakage.
On aftermarket gear sets, the pinion gears are etched with a gear set number. The recommended pinion depth is etched next to the set number. Pinion depth is the distance from the rear of the pinion to the centerline of the carrier. You will also find a set number on the ring gear along with a backlash spec. Currie techs work with these specifications and adjust accordingly if necessary.