Maybe once a week I go on patrol of things that need to be flagged and cleaned up (migrated, closed, etc.)
A common thing I do is look through the Ubuntu, Linux, OS X tags (as it seems many of these questions are often better suited for Ask ubuntu, Super User, Server Fault, etc.)
Often, I may flag several in a row (like 5 in under a minute)
I've never had more than 10 awaiting review either. That's a limit I've imposed on myself.
Is there a known time constraint for flagging as to not appear as being abusive or anything else I should be aware of? (I know there is a limit to the number of flags per day, although I've never reached it)
If the vast majority of the flags are helpful, is this even an issue? Should I not worry about it since it is in no way abuse?