A myth based on another myth... OTOH, it's definitely easier to be more productive if you cut corners (or "incur technical debt" if you want to say it in a more sophisticated way). Generally, a more productive developer will know where to focus their effort, e.g. understand the business logic so they don't spend time handling cases that won't happen in practice, know where tests are most needed and leave other areas for later, automate repetitive tasks or find tools that make a task easier, etc.