I see you're in Washington, a high moisture state (at least most of it). I had problems with my low-use Dakota when I let it sit for more than a week, it would stumble and be hard to start, stall, hesitate, etc. until ran for 10-15 minutes or so.
After a while I figured it was phase separation of E10 so i started using E-Free gas, adding dry gas (which acts differently than Ethanol), and driving it more often. Problem went away.
Slacked off and it sat with E10 and problem came right back.
So I think your 30 minutes once a week is a good regimen, it keeps the fuel mixed up. The problem with E10 is it absorbs moisture from the air and then the alcohol/water mix separates to the bottom of the tank, and the engine has a hard time running on just that. Just going for a drive gets it mixed up again.