Non-symetric window layout: why?

Working with WP for 11 years, discovered this theme and am absolutely amazed. <3

Question: In my blog post overview (window view 2 columns wide), why are the windows of separate sizes? I don’t think this should be the case and cannot figure out what the prob is. Thanks!

Screenshot is available here:
http://eiko-fried.com/wp-content/uploads/Screen-Shot-2016-10-14-at-19.48.04.png

The site is http://psych-networks.com/

Thanks for your feedback!