So far, the only soap that has been inconsistent and has given me hard time to get the lather right each time was Cade. I have 15-20 soaps and creams in rotation, so I don't use each one of them that often. When I'm in mood for Cade, I still have to be careful and try to remember how to lather with it. When I get it right, it rewards me with a great shave. If it wasn't for the great scent, I doubt I'd bother playing with it. I believe it likes a very dry brush to load, and add water very slowly. It's easy to miss the point when the lather is ready and to put too much water. Also, I need to add some water to it before each pass.
This would be a good soap to do a fidelity run with- use it every day for a month or two and you will get much faster making the lather with this, and with other soaps. As you will be able to "spot the markers" faster as you create the lather.