I've seen many a times questions are put on hold as unclear within some hours of posting. For example, this question was closed within 3 hours of posting.
Suppose in some country there is a user who posted a question and slept. Meanwhile his question was put on hold after, say, 6 hours of posting. He got no time to improve his post in those 6 hours. And if he improves that question after those 6 hours, it may take up a while to reopen the question. And if another user finds the question interesting and knows the answer, he can't answer it since it is now put on hold and at later stage when question is reopened he forgot to answer that question which was not marked as favorite or lost the interest. We may lose a great answer. Sometimes, I wonder that this might also create a negative impact on the earlier user even when it is not intended to be.
In my opinion, we should cast close votes especially the most loved "unclear" vote at least after 2 days of posting when there is a scope of improvement in the question. Also, closing a question require 5 votes and if you are the fifth one to vote (from question page or even in review queue), I'd like to urge to take sometime and think before closing because that last vote might close the question (may be) incorrectly and indefinite time. Since closing takes no time and sometimes reopening takes appreciable time.
The main goal of posting this is to attract opinions of different users and aware others about that.