Is it ok to run an MBAM scan & and Avast scan at the same time? For example, running a full system scan with both at the same time?
I have always done one at a time just in case it caused any conflicts running them both together but, i am now wondering if this is necessary?
In theory, they could trip over each other if there were detections, and possibly detect each other in the process of scanning…
In any case, save some processing power for yourself and run them separately 
It is quite okay to run an avast scan with a mbam scan to save time. However, it might render your pc unusable until one of the scans is done.
I wouldn’t recommend it.
I don’t think it will save time as there would be an element of CPU time, RAM swapping, and hard disk thrashing, etc. depending on system specs and the amount of data to be scanned in both scans.
I just schedule an avast Quick scan at a time when I know the computer will be on and not generally busy, following that up 15 minutes later by an MBAM Quick scan. On my system both of these Quick scans only take a few minutes each (MBAM being slightly slower).
Even if it would be possible, and even if it would save you some time (it doesn’t), the simple hardware trashing (HDD) is enough reason not to do it.
Just to be clear, it is not going to instantly break your hardware, but the hardware’s useful life expectancy will be lowered in time.
Ok that makes sense. I see that people seem to mostly use quick scans as i do. Occasionally i will do a full system scan but how often is it really necessary to do a full system scan?
I don’t do them at all on a routine basis now, a long time ago I did them once a months and Quick scan weekly.
In all honesty that is just being a creature of habit as with a resident on-access antivirus like avast, the need for frequent on-demand scans is much depreciated. For the most part the on-demand scan is going to be scanning files that would be otherwise be dormant or inert. If they were active files then the on-access file system shield would be scanning them before being created, modified, opened or executed.