I have recently seen a few cases where questions have been closed very quickly (after a few hours), usually with a "question unclear" motivation, but with no further comments to the OP. Examples are:
1) How are colors outside the standard RGB color scheme perceived? (also highlighted in this meta post)
My feeling is that in all these cases, the questions were dismissed too quickly, without giving the OP a chance to edit and clarify his question. In case (1) the question was initially closed for being off-topic, but was then reopened. In case (2) the question was closed for being unclear, but in my opinion it was clear enough after some edits, and my answer was apparently what the OP was looking for; I have voted to reopen it. In case (3) there has been no further discussion --- possibly the OP gave up after the question was closed.
I agree these questions have been borderline off-topic and/or unclear, especially in the first posted version. But I think it is important that we in such cases point out what the problem is, and allow the OP to attempt to revise the question, rather than just closing it with no feedback to the OP whatsoever.
One danger with closing too quickly is that it is likely to be discouraging towards newcomers; it feel it makes Biology SE appear less welcoming. Also, we should recognize that it may actually be difficult for the OP to formulate the question clearly if he/she is uncertain or confused about the topic. Providing comments and allowing the OP to revise the question are then necessary steps towards an answer. (Personally, I have learnt over the years that in science, formulating good questions is often harder than answering them, and so I have a lot of respect for this process.)
For these reasons, I think it is important that we err on the side of caution when considering closing questions. My view is that a poorly formulated or borderline-relevant question that remains open for a while doesn't really hurt anyone, but premature closing of a question can be rather damaging because of its discouraging effect.
I recognize that review of questions is a somewhat thankless task where we have too few hands, as pointed out in another recent meta post, and that mistakes will be made. But I would suggest that we try to give borderline cases the benefit of doubt, especially when the OP is a new user, so as to be inclusive as a community. I'd love to hear any comments you might have.