Jelqing primarily forces blood laterally — expanding the erectile chambers outward. The primary direction of expansion from repeated engorgement pressure is circumferential. This makes girth the primary target of jelqing.

Length from jelqing is possible in theory — the same tissue expansion principle applies longitudinally — but the mechanical force in a standard jelq stroke is not primarily lengthening. Dedicated stretching exercises target length more effectively.

The honest community consensus: jelqing for girth, stretching for length. Combining both in a routine is the standard PE approach.

— GirthVsLength_Greg