Sometimes the policies are so vague and ambiguous I advise clients to go for a pre-app rather than them waste money on plans if I think their proposal is dubious. As someone else suggested sometimes the official policy is just a vague comment about avoiding terracing, some interpret that as setting in from the side boundary, some a set back to the front elevation or both. They don't always give clear concise guidance with recommended dimensions, that would be far too helpful.
I would expect the designer to know how to avoid terracing, and if that is all the policy says, then there are several options. The planners will know the options as will the inspectorate so it should be relatively simple to come up with a design or be confident that if need be, an appeal would be likely to succeed.
I tend to find that pre-application advice (just like LDC's) is more often used by inexperienced and amateurs. A designer should be confident in his knowledge and skills, and thats what a client wants. Don't bow to planners, but push for the best outcome for the client.
Advice should be limited to something that is going to be non-standard, to get a feel for how it would be interpreted