Hmmmm.... this might explain why I've felt the need to add lots of butters and softer oils. If you keep your CO at that 30% approx. would it eliminate the need for so much other moisturizing oils and butters? I too have very dry skin. I learn something every day here! Thanks!
It depends on your skin type and what you prefer. Some people may absolutely love a bar made with 30%-32% CO, other people won't. When I first started soaping, I read to use CO around 30%-32% so I did. I liked my soaps but I was disappointed by how much they dried me out. On the other hand, my BIL really liked them.
After reading and asking questions, I dropped my CO %, upped the castor oil % and upped the SF just a little to 7%-8%. I was much happier with the results. The downside to this is it did make my soaps a little softer but not enough to bother me.
When I started to use dairy products in my soaps, I found I could raise the CO % because the dairy seemed to offset the drying effects of the coconut.
This is just what I experienced. There really isn't any right or wrong amount. You'll have to experiment and try batches with different % of CO and see what works for you.