Well, it's not a waste of time. While it scans it checks your computer of viruses.
Folder that you mentioned (microsoft office\office\) has so many subfolders, so you can not possibly see what subfolder is being scanned at that particular moment. I'm asuring you that avast! doesn't scan any folder twice.
If some antivirus scans all your hard drives or partitions in short period of time, let's say about 10 seconds, like we all would like to see (which is by the way impossible), that means that antivirus doesn't check properly.
Relax, and believe me, this is normal avast! behaviour...