If you are growing an indoor crop and want the most trichomes (resin), leave your plant in the dark the last 2 or 3 days before you pull them up. this is when you should flush the plant of nutrients.

in leaving the plant in the dark, you will force the plant to produce more resin because the plant thinks it's going to die. the marijuana plant produces resin as a means to help catch more pollen from the male plant. however if it's not pollinized, the plant keeps producing resin. well when you leave it in the dark it goes into "overload" and vigorously tries to catch pollen--by producing resin.

in response to your question as to why white widow is so different, it is determined by the plant's genetics. some humans are more prone to develop cancer due to genetics--some marijuana plants are more prone to develop higher THC levels for the same reason.

i got that from the cannabis grow bible.