It was Twain (I think?) who said something like, If I had more time I'd write a shorter letter. I'm inching up on 20 years into my career and I have everything — work, volunteerism, skills, education, etc. — down to two pages. Yet I see resumes sometimes from people with five-10 years of experience that are four (or more) pages long. I think that's something you only really learn over time.