“In considering reasonableness… it is, in my opinion, perfectly clear that the duty of the judge is to take into account all relevant circumstances as they exist at the date of the hearing. That he must do in what I venture to call a broad, common-sense way as a man of the world, and come to his conclusion giving such weight as he thinks right to the various factors in the situation. Some factors may have little or no weight, others may be decisive…”