Deep scratching is a recovery tool used to recover damaged casings from OVERLAY
It is accomplished by scratching the surface of the casing to a depth of a few milimeters with a fork or similar device.
If you have successfully harvested a good first flush, leave your casing alone in the fruiting chamber. Mist it, bring water content back up to where it was prior to the first flush, and wait for the second flush.
Do not deep scratch, unless it is having problems pinning, problems associated with overlay, which is directly related to over incubation, and a lack of air exchange.
Deep scratching after a healthy first flush is BAD INFORMATION. Pins for your first and second flush are produced during the initial intiation. If you deep scratch after harvesting the first flush, you kill all the pins for the second flush. This deep scratching at this point does two things, it prolongs the time between the first and second flush, and more importantly, it will spread any contamination that might be presently contained.
Some species of mushrooms actually benefit from deep scratching prior to the first flush, but cubensis is not one of them.