depends on the strain and style of growing, also lighting can play a role, you get more stretch going from 24 hour light to 12/12 than you do from 18/6 or 12/1
i have definitely noticed a difference, i used to veg at 24-0 and got a lot of stretch, and upon switching to 18-6 i found it was a lot less. i have also read other people noticing this as well. i think it's because the plant freaks out a bit more, going from 24 hours light to only 12, as if it were suddenly shaded by another nearby plant, and it's first impulse(if plants have those lol)is to stretch and try to get out from under the perceived obstacle blocking it's light. as a rule of thumb the less light a plant gets the more it tends to stretch, in veg anyway, this goes for most plants of any species. it is also written around here somewhere, i know i'm not the only one to notice the phenomenon...I have never heard that before - thanks for that info! Just out of curiousity, did you notice this yourself or is it just common knowledge I somehow let slip by. Thanks!