>I generally tend to interview every year to see what's out there in the world (sometimes I find something worth switching for, other times not). I'm not even looking very hard but have had 4 interviews in the last month.

You've been interviewing forever. You're the well practiced pickup artist of job searching. Of course you'll be getting the call backs over the other 1000 applicants who don't have the same experience level applying. You "just know" how to read between the lines and tailor a resume, whip up a cover letter, etc whereas they're making mistakes.