This sounds a lot like the common practice of flushing during the couple weeks before harvest. The general idea as I understand it is that you stop feeding the last couple weeks so the plant has to look inward for nutrients and starts consuming what it has stored up in the leaves and the flowers. Supposedly, it can help the end smoke have a smoother, less chemical taste and even supposedly burn better (ie...if you don't get white ash when you smoke you didn't flush right type claims).
While many people swear by flushing, there is a growing number that feel it is more of a myth that has grown to the point of near gospel, and that flushing your plants for the last few days or weeks is a bad idea.
Best debate I've read on it so far is in the thread over in
@pop22 's mythbusting section of the forums:
https://www.autoflower.org/threads/flushing-the-myth-that-wont-die.56274/