Toward the end of my first year in business, I noticed that more and more of my time was spent working around invalid code. Layout issues that would have been trivial to fix in a valid, error-free template would take significantly longer to debug in a live page that had a few hundred validation errors. It was a matter of figuring out which parts of the page weren’t causing the errors, so I could focus on fixing the problematic section. But when the page’s markup has three or four hundred validation errors, this process quickly becomes a time sink. A necessary one, but a sink nonetheless.
So by year’s end, I found that approximately fifteen percent of my time was spent mired in invalid code

