Multiplicity of Right Answers

This is how I see it and how I explain multiplicity of right answers coming from multiple trainers:

Everyone has to have many tools in their tool box. Many tools do the same thing, for instance a socket set and a wrench loosen bolts. Both will get the job done but sometimes you need one or the other, depending on the situation. That's why you always want to make sure all your tools are ready and honed for the job. 

Not all horses and not all scenarios are the same. A good rider matches their tools with the day, the horse, the scenario and every aspect of context. 

Every trainer is right, depending on the context that only the rider will know.