In general you are correct, but coconut oil is a known outlier. Because coconut oil is so cleansing, recipes with a lot of it normally use higher than "normal" superfat/lye discount. My 80% coconut oil salt bars are good with 20% superfat, and the 100% Coconut oil / 20% superfat has been written about in a number of places on this forum and even here: http://www.soapqueen.com/bath-and-body-tutorials/cold-process-soap/defying-the-rules-of-soapmaking-100-coconut-oil-soap-with-aloe-vera-and-a-mantra-swirl/ Its a recipe that is definately on my list of things to try.
Well from my experimenting with superfat on about 20 batches of soap more than half of them cured with DOS or spoilage issues because of too much superfat and the other ones were lye heavy...
The wonderful world of experimenting.. Superfatting is usually recommended to stay below 15%. But also the lye to stay at 5% or above... the world of soapmaking gives you a lot of play time to see what you can get away with and what you cant.
Everyone has their own opinions and rules.. thats the fun part about it. Just be careful in the process