Also depends on which scanner we are talking about, since i use EAM and as everyone knows this scanner is kinda slow i only scan like once or twice like i said before But if it was something faster like HMP or AV's with the fingerprinting technology that only scan new and changed files then it would be another thing
I answered monthly, but it's probably less than that. Maybe once monthly with Avast (quick scan) and every other month with MBAM (quick scan.) That's if I remember. So far, nothing found.
Probably about once in a year, and even that only for creating the KIS' iSwift database so the real-time protection works faster and doesn't scan those files which were scanned during the full scan.
I use prevx free, which scans my computer daily provided sufficient idle time. I also use it to run short scans after it updates or if it finds an infected file (usually false positives). Beyond that, I run a quick scan with Emsisoft Commandline Scanner maybe every week or two, and something more comprehensive only if I have a reason to suspect a problem.
Scan weekly if I think about it...honestly, I don't see the need with KIS 2011 (and most free/paid AV protection), although anything is possible. I must be looking for love in all the wrong places...unless I blindly click on something like a "Koobface" virus or whatever that was back in the spring of this year that tricked a lot of casual users, I don't see too many danger zones for the most part...knock on wood!
I do a full scan once in 1 or 2 months with Avira, Sas, and MBAM, and eventually if i get suspicious about something. I've never had any problems.
I wipe more than I scan. An hour to scan or an hour to wipe, it's an easy choice. How many wipes does it take to get to a failed HD? 3 years with an average of 1 a week, no issues yet.