I flowered some green poison 3 weeks longer than attitude seed bank suggested. I basically flowered my girls until almost all the leaves were dead. Did I waste my time? Did I gain anything? Did I harm the quality? Did flowering longer help achieve my ultimate goal of the best quality I could have grown?
THC will degrade after a certain point of maturity. Once a plant is ready for harvest and has pretty much flowered all she can, there really is no point in extending the flowering stage when no more growth can come out of it. You also run the risk of the plant going hermie on you in a last ditch effort to save itself (procreate for the future), remember these are living things and they want to survive. Your buds will be a very couchlock high though It'd be like growing tomatoes and waiting until the plant is basically dead before cutting off the tomatoes.