From my experience it does more than just "dry out and get harder". It also finishes the reaction. Soap that has been allowed to cure for a full 7 weeks is much milder. The soap Ive used earlier than that tends to be harsh
That's great! That's why testing each bar is so important. I just released a video about our R&D process and talks about lather testing as well! ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-UhD5vgDB98U.html