I build code that allows the usability on as many screens as possible. I try to engage the client to think about user journey through the campaign based on their data results. This empowers the client to make intelligent decisions that can streamline a project and focus on what matters to their users. Useful data for code building includes devices, browsers, and versions used.
For email coding, there are a lot of variations, so we keep the code clean and consistent. We use modular templating for streamline production. If we are handing over code to a client, we include a comprehensive guidebook that explains the reasons why we code the way we do for email, and how our templates work for rapid campaign productions.
Sometimes, we add enhancements, like carousels and hamburger menus, but these have limited email support and only offer advantages if the client data supports it.