Northern Mainline (RQS freebie)

Whelp. Here goes another free seed. Everywhere says, "don't top, don't mainline, don't touch, don't anything but LST", so I would like to find out why. I've managed to keep a Royal Dwarf under 12cm tall and a White Widow auto under 15cm tall, both within a 20x20cm pot radius. They are mostly regular in shape, but I trained them in a semi-traditional bonsai form called Moyogi (without pruning inside and up/down "branches" and fan leaves). Don't get me wrong - they look great, especially now they are in flower - but I wonder if I might have been able to train them in other styles..? As such, I am going to embark upon some bonsai training for these free seeds (even though Northern Light probably isn't the ideal plant for it - but they're free...) and will grow each of them in a different style: Fit 1: Quasi-Hokidachi / Quasi-broom (this one, mainline) Fit 2: Ikadabuki / Raft (severe LST) Fit 3: Fukinagashi / Windswept (LST & defoliation) Fit 4: Kengai [han-kengai] / [semi] Cascade (severe LST) Yields be damned..! (although I will be comparing the results not only on appearance, but also on harvest volume since that's the reason people generally grow cannabis) I guess they will be a month or so apart, so this ought to keep me occupied for the summer and harvest season :D