I feed nitrogen from seed to harvest. I also grow in soil with dry amendments "gaia green" vs liquid feed, but the plant still uses nitrogen in its flowering stage 100%. Its a myth that it does not use it. Granted to much nitrogen in some plants can cause them to not produce as many flowers or any at all and focus on leaf growth. I don't feel cannabis is like this but to much can hurt your yields as it will lock out other nutrients and it can make the feeding solution to strong in terms of EC/PPM.
guessing you mean fractal of branches as in bushing out or creating more growth points. Nitrogen will not affect this as much as training techniques do or genetics.
Good Luck & Happy Growing!
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