I only (involved in internship) drove my Boxster 1000 miles this summer and am changing the oil before storage; I also flushed the brake fluid this summer.

Once a year for me
 

If it reaches 5 K miles or not I change the oil about this time every year...usually I only get around 4 K miles per year on my Boxster. I am due (by my own schedule )right now.....but working 65+ hours per week leaves precious little time. I am also just past 60 now and do not have the energy I had just a few years ago