I think from a non-geek perspective, "I read a lot of books" might mean "I enjoy reading, perhaps we can talk about books we've read?" Whereas "I read about 5

I think from a non-geek perspective, "I read a lot of books" might mean "I enjoy reading, perhaps we can talk about books we've read?" Whereas "I read about 5 books a week" sounds more like "I count how many books I read so that I can one-up anyone who thinks they are as smart as I am." A non-geek who reads 5 books a week might admit the exact figure if probed, but would be more likely to look slightly embarrassed, to imply "yes I know that makes me odd" and "don't dislike me; I'm not trying to seem superior but you asked."