[16] The manner in which the discretion is to be exercised of course depends upon the particular facts of each case, which are infinitely various. In some cases the circumstances may militate against the exercise of the discretion at the first opportunity. But in my respectful opinion, the grounds assigned by the learned sentencing judge for declining to take into account any part of the substantial period of pre-sentence custody in this case were irrelevant. The sentencing judge's reliance upon a view that the applicant would probably be convicted of the other alleged offences, in respect of which his counsel had signalled his intention to plead not guilty, was inconsistent with the presumption of innocence to which the applicant was entitled; and his Honour's reference to the potentially curative effect of an application to re-open the sentence in case that view should prove to be incorrect failed to give effect to the policy of the law that favours an end to litigation.