There are too many decisions, technical details, and active changes to have someone come in and give direction from on high at intervals.
Maybe at the beginning it could make sense sort of, but projects have to evolve and more often than not discover something important early on in the implementation or when adding "easy" features, and if someone is good at doing software design then you may need them even more at that point. But they may easily be detrimental if they are not closely involved and following the rest of the project details.