harvesting a dwc

i read somewhere a while back about when plants are ready for harvest that you should leave them in for two more days with lights off before chopping down has anyone got any knoledge on this and do i need to do this
thanks in advance

The logic behind this is....

Plants produce THC during the dark period as a response to the UV lighting they received during the day. This is why it's best to harvest at the end of the dark period, as light degrades THC. To take this a step further, some ppl let their plants sit in total darkness for 48 hours before harvest to encourage a little extra THC production. Whether this works or not is beyond my knowledge.

The main reason for harvesting in the dark is due to the fact that plants are "sleeping" and therefore not feeding.
Less ferts in your buds and stems at harvest basically.