Interesting. So there's no live protection? I've completely overlooked this .....
Nah man, MSE is live protection, but since its made by Microsoft, it's pretty lightweight on resources and runs in the background. I emphasize protection and resource use equally. MSE very highly rated as virus protection software goes; imo better than avast, AVG, and Avira. Uses less resources than the other 3 too. I just have a standard scan set for once a week, just because I'm anal.
Malwarebytes isn't live protection, but it's one of the best pieces of spyware/malware software in the business (and free). Like I said, I just schedule a scan once a week on it. It doesn't run on my system the rest of the time.
I absolutely hate live spyware protection like Spybot Search & Destroy, always popping up and bugging you and hogging resources. Malwarebytes is better anyway.
And note, once a week is probably overdoing it. I'd be fine with once a month. But again, I'm anal.