1. Fully formed but still clear will provide a cleaner ‘up’ high with less sedative effect; this is the best window for heavy Indicas.
2. Fully formed and turning slightly cloudy or milky; this is probably the best time to pick most hybrids available today.
3. Fully formed completely cloudy or milky with at least thirty percent of the heads turning amber; this is usually best window for the late maturing Sativa’s such as Haze. This is also a good window when using the plant primarily for Hash production.
The mistake to try and avoid is harvesting before the trichomes are fully formed, so as mentioned in the guideline; most growers whom use this method, harvest at the point in which the majority of the heads are cloudy. Harvesting before this window will produce bud that is less potent, containing less essential oils and trepans, causing your finished stash to take on a grassy or green taste, even if it is dried and cured correctly.
That is str8 from the link Sourpuss posted + nowhere in the article does it say 70% clear is when to harvest.^^^
Fully formed being the keyword he used> if the Calyx aren't swollen then they haven't fully formed yet.
I would never bash subcool> but I don't have to take his every word as fact.
We can all do our own experiments + conclusions which I've already made for myself.