In my opinion the last stage should consist of the following:
Thinner peeling
skin should be more water proof
SKIN IS MORE SENSITIVE TO TOUCH (important one)
The lower part of my bottom lips has been goin threw the barrier stage & its much more sensitive to touch than the rest of the bottom lip. When i touch the ec area, its like my lips feels the finger but not as much as the healed parts (if you know what i mean)