I usually do a balance between grow and bloom a week before the flip it seems to make them start showing signs of flower a little sooner. I think there are a lot of things that can increase or reduce the stretching and I sure hope I figure them out this grow. I think the media makes a big difference, soil seems to hang on to nutrients longer than water or coco so a flush may help, defoliation seems to make a difference, more blue light really makes a difference and bud pinching may help but I have not tried a side by side test yet. If its a worry, I will super crop the branches in 2 places to make a dog leg or even N shape to the reduce the height.