I occasionally have mixed models that take more than 3 hours to converge. This was not a problem when Studio ran on my laptop in a virtual server. I could instead run it in the full SAS package, which I can access via my institution (Victoria University, Melbourne), but I have not bothered to install it since transitioning to Studio, mainly because I write programs for students to learn SAS and to run themselves, and it's far easier to do that via SAS ODA. So I envisage something in the preferences that allows a temporary extension to 12 or 18 hours, say (to allow a program to run overnight), which would automatically revert to the 6 hours when the session is terminated. Naturally you could monitor it for fair use.
By the way, it's not clear what the 3 hours of inactivity means. If I have a program that runs for 4 hours, does that mean 4 hours of inactivity?