You say: "Learning styles are often used as a catch-phrase to say that the training will be suitable for different tastes and abilities." I think the heart of the issue is that a single training method can not be applied to different tastes and abilities. I think you need a variety of training interventions in order to accommodate how different people learn. It should not be about trying to build the "ultimate" course that meets all needs, rather it should be about building many courses that each take a different approach to the topic, so learners can select the one that best suits their requirements.