There are times when a certain question is proposed to be off topic. See the comments to Who were the original users of Ktav Ashuri? for a recent discussion.
There is an obvious quick fix to keep that particular question on topic.
How quick should we be to close it, leaving the OP wondering exactly how to fix it, vs offering the easy solution to the OP?
Should there be more of a leeway for an OP who is new to the site? Give them some kind of learning curve?
Should it matter how popular (by up-votes) the question is? I'm not suggesting to keep off topics open due to their popularity, but should we be offering more help to fix a questionable post due to its popularity?
Close if it is closeworthy. Bring something into scope if you want to. (That's my rule of thumb. You can ask on Meta if you think it should be different. My logic is 1) I can't leave closeworthy things open, 2) I can't be expected to try and bring everything into scope somehow.)