WMATA cutting back too soon on PM rush headways?

[CKD]

http://infosnackhq.blogspot.com/2008/08/anatomy-of-peak-ridership-for-wmata.html

This guy's conclusion seems to be that WMATA is cutting back on the PM rush hour headways way too soon.  However, he is only using one line for his analysis which just happens to be the busiest one of all.  But, he is right about that line in particular, given how many major gathering points the line hits as it goes across DC and Maryland.  There's just so many people who have errands to run or places to see or go to after work.