Does planning content for search and answer engines add time to a website build?

It can, and the amount depends mostly on how much content your site needs and how much research is already complete. Planning may include researching real customer questions, writing concise answers, organizing pages around those needs, and creating useful internal links. Accurate structured data may also be added where the page and content qualify, but there is no special schema that automatically makes a page ready for answer engines. Doing this work during the build is usually more efficient than reorganizing the site after launch.