Look at any lawyer's office and you'll see shelf upon shelf of law books, despite their spending years at law school to perfect their trade. Unless you're in a coding interview, it's not about what you know, it's about knowing what you don't know, and knowing where to find out. I've been known to google some really basic stuff just because I'm jumping between multiple languages for a single project, and it's faster and easier to google whether I need to use '+' or '&' for string concatenation than it is to disrupt my flow by taking a chance and then having to backtrack to fix it later.